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  • 1985-1989  (9,234)
  • 1986  (9,234)
  • Chemistry  (7,918)
  • Cell & Developmental Biology  (1,316)
  • 1
    Electronic Resource
    Electronic Resource
    Eupatorium cannabinum L. (1986)
    Springer
    Pharmacy world & science 8 (1986), S. 245-251 
    Details
    ISSN: 1573-739X
    Keywords: Analysis ; Antineoplastic agents ; Biosynthesis ; Botany ; Chemistry ; Cytotoxins ; Eupatorium cannabium ; Sesquiterpenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A review onEupatorium cannabinum L. is given, including botany, history and constituents. The sesquiterpene lactones are discussed in more detail, covering their biosynthesis, isolation, analysis and biological activity. Special attention is paid to the cytotoxic and antitumour activities of the sesquiterpene lactones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01960068
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  • 2
    Electronic Resource
    Electronic Resource
    Editorial (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 1-1 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060102
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  • 3
    Electronic Resource
    Electronic Resource
    Isolation of cilia from porcine tracheal epithelium and extraction of dynein arms (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 25-34 
    Details
    ISSN: 0886-1544
    Keywords: respiratory cilia ; dynein ; ATPases ; porcine trachea ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Milligram amounts of mammalian ciliary axonemes were isolated from porcine tracheas. These were reactivated upon addition of ATP, indicating intact functional capability with a mean beat frequency at 37°C of 8.2 Hz. Electron microscopy showed typical ultrastructure of the isolated demembranated axonemes. Electrophoresis into polyacrylamide gradient gels containing sodium dodecyl sulfate revealed reproducible protein profiles from ten different tracheal preparations. Four major protein bands were observed in the 300-330 K molecular weight region, as well as tubulin at 51-54K. Extraction of the isolated tracheal axonemes with 0.6M KCl removed the outer dynein arms seen in electron microscopic cross-section of axonemes, preferentially solubilized two of the high molecular weight proteins at 320 and 330 K, and resulted in a three- to four-fold increase in ATPase specific activity. Sedimentation of the dialyzed salt extract on a 5-30% sucrose density gradient and subsequent fractionation yielded two peaks of ATPase activity. The faster migrating, 19S major ATPase peak correlated with the 320 and 330 K proteins, and two other proteins at 81 and 67 K. The slower sedimenting, 12S minor ATPase peak corresponded to a 308 K protein and two smaller proteins at 33 and 48 K. Thus, the outer dynein arm of tracheal cilia appeared to be associated with at least two high molecular weight proteins. These results demonstrate that adequate quantities of functionally intact axonemes can be reproducibly isolated from porcine tracheas, allowing further fractionation and analysis of mammalian cilia.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060105
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  • 4
    Electronic Resource
    Electronic Resource
    Masthead (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060301
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  • 5
    Electronic Resource
    Electronic Resource
    Prelimlnary report on the ultrastructural organization of the contractile appendix of Tontonia appendiculariformis (ciliophora oligotrichina) (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 217-224 
    Details
    ISSN: 0886-1544
    Keywords: contractile system ; microfilaments ; microtubules ; endoplasmic reticulum ; ciliophora ; oligotrichina ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tontonia appendiculariformis is a marine planktonic ciliate with a long tail. The tail can contract rapidly, becoming transformed into an oval mass one-twentieth of its original length. The highly complex ulrastructure of the tail is described here in detail. A large part of the volume of the tail contains numerous more or less parallel membranous tubes. The membrane of the tubes has numerous invaginations and is probably derived from the smooth endoplasmic reticulum. This tubular material forms a continuous layer around the tail, interrupted in only one region, which contains cilia. Associated with the cilia are basal fibres with a periodically banded appearance. The tubular layer forms several folds separated by hyaloplasm containing many mitochondria. The pellicle of the tail is thrown into numerous pleats. It comprises a perilemma, a plasmalemma, and complex alveoli, but epiplasm and microtubules are absent. The alveoli appear to form septa within the folds of the layer of membranous tubes. In the region where the tail is attached to the body of the ciliate there are conspicuous bundles of microtubules and microfilaments. The membranous tubes and septa appear to be connected to small bundles of microfilaments, which presumably represent the contractile material. However, we consider the membranous tubes as potentially active in producing the change in shape. Although the structure of the tail of Tontonia is unique, there are certain similarities to the stalk of the Tintinnina and also to the motile extension of the dinoflagellate Erythropsidinium.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060221
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  • 6
    Electronic Resource
    Electronic Resource
    Robert Day Allen (1927-1986): An appreciation (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 249-255 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060302
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  • 7
    Electronic Resource
    Electronic Resource
    A model for the molecular basis of filament contractility and sliding as demonstrated by helix models (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 229-236 
    Details
    ISSN: 0886-1544
    Keywords: α-helix ; filament motility ; filament contractility ; filament sliding ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The twisting behavior of α helices has hardly been considered hitherto with regard to the function of proteins. The well-known electrostatic repulsion between the highly charged side chains, which depends on their interaction with ions, is absolutely connected with torsional rotations of the helix as long as its hydrogen bonds hold. This means a direct transformation of chemical into mechanical energy. However, the stability of a twisted single α helix with charged side chains is low in an aqueous environment. It may easily ball up to form a globular molecule with nonhelical regions of the polypeptide chain. This corresponds to a primitive contraction that obviously occurs with spasminlike proteins that contain strongly twisted filaments as Salisbury [J. Submicrosc. Cytol. 15:105-110, 1983] has shown. Steps that increase the stability and rigidity of α helical filaments are (1) the formation of coiled-coils, (2) self-intertwining (“telephone cord phenomenon”) or intertwining with other coiled-coils as shown with the intermediate filaments, and (3) association with cytoskeletal elements (microfilaments, protofilaments of microtubules) that contain globular subunits. These coarser elements are rotated by winding and unwinding of the smaller helical molecules and thus transmit the torsion produced in the α helices to the microscopic level by the sliding (screwing) motion and the shearing effect that is connected with the waves of a rotating helix. Particles are transported if connected to the helical side arms. Since the displacement of the side arms seems to occur along the single protofilaments of a microtubule, a rotation of these protofiiaments is suggested. The bidirectional transport of particles along single microtubules may be explained by the association of left- and right-handed helices with the protofilaments. According to the models, parallel and antiparallel sliding of neurofilaments and neurotubules is suggested.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060223
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  • 8
    Electronic Resource
    Electronic Resource
    Regulation of ciliary motility by membrane potential in Paramecium: A role for cyclic AMP (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 256-272 
    Details
    ISSN: 0886-1544
    Keywords: ciliary motility ; cAMP regulation ; swimming speed ; membrane potential ; detergent models ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The membrane potential of Paramecium controls the frequency and direction of the ciliary beat, thus determining the cell's swimming behavior. Stimuli that hyperpolarize the membrane potential increase the ciliary beat frequency and therefore increase forward swimming speed. We have observed that (1) drugs that elevate intracellular cyclic AMP increased swimming speed 2-3-fold, (2) hyperpolarizing the membrane potential by manipulation of extracellular cations (e.g., K+) induced both a transient increase in, and a higher sustained level of cyclic AMP compared to the control, and (3) the swimming speed of detergent-permeabilized cells in MgATP was stimulated 2-fold by the addition of cyclic AMP. Our results suggest that the membrane potential can regulate intracellular cAMP in Paramecium and that control of swimming speed by membrane potential may in part be mediated by cAMP.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060303
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  • 9
    Electronic Resource
    Electronic Resource
    The lack of interaction between vinculin and actin (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 48-55 
    Details
    ISSN: 0886-1544
    Keywords: vinculin ; actin ; adhesion plaques ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Vinculin was purified from chicken gizzard by a modification of the method of Feramisco and Burridge [1980; J Biol Chem 255:1194]. Vinculin did not alter the viscosity of actin as measured in an Ostwald viscometer, nor did it affect actin polymerization as measured with the fluorescent NBD-actin assay. Sedimentation experiments demonstrated that vinculin did not bind to actin, and electron microscopy of negatively stained specimens indicated that vinculin did not aggregate actin filaments into bundles. These results suggest that vinculin, by itself, does not interact with actin at least under commonly used conditions to assay actin-protein interactions in vitro.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060107
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  • 10
    Electronic Resource
    Electronic Resource
    Fungal nuclear behavior analysed by ultraviolet microbeam irradiation (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 35-47 
    Details
    ISSN: 0886-1544
    Keywords: microbeam ; microtubules ; nucleus ; cytoskeleton ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During hyphal tip growth in the fungus Basidiobolus magnus, nuclei normally maintain a constant distance from the advancing cell apex by continuously migrating forward. It is not known whether the mechanism that produces nuclear movement also mediates nuclear positioning, or whether these two processes are under separate control. By irradiating small cytoplasmic regions with an ultraviolet microbeam, the coordination between movement and positioning could be disrupted. Regardless of the distance of the target from the nucleus, anterior irradiations (those ahead of the nucleus) caused the nucleus to stop or move backwards, whereas posterior (behind the nucleus) irradiations caused an acceleration in the nuclear velocity. The nucleus retained its ability to move following irradiation, so there was only loss of control over normal positioning. These results suggest that movement and positioning are mediated by different mechanisms. Quantitative microtubule analysis demonstrated that microtubules in the target region had been depolymerized, but in other regions of the cell they were apparently normal. We suggest that the depolymerization of microtubules affects nuclear movement by altering the tensile strength of the cytoplasm, and that cytoskeletal tension mediate nuclear positioning.We also found that accelerated nuclear movement could occur when most of the microtubules surrounding the nucleus were depolymerized. A comparison of the microtubule population surrounding the nucleus in unirradiated versus irradiated cells suggested that microtubules move with nuclei. Therefore, the nucleus does not appear to move via a direct interaction with microtubules.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060106
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  • 11
    Electronic Resource
    Electronic Resource
    Evidence for regulation of lamellipodial and tail contraction of glycerinated chicken embryonic fibroblasts by myosin light chain kinase (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 640-648 
    Details
    ISSN: 0886-1544
    Keywords: cell model ; lamellipodia ; phosphorylation ; Ca2+-dependent contraction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Permeabilized cell models of muscle and nonmuscle cells have proven useful for examining the regulation of actin, myosin, and other cytoskeletal proteins during cell contraction. Upon addition of Ca2+ and ATP, glycerinated chick embryonic skin fibroblasts retract their tails and lamellipodia. Ca2+-independent contractions are obtained by preincubation of cell models in Ca2+ ATPγS, followed by EGTA and ATP addition, or by addition of trypsin-treated myosin light chain kinase that no longer requires Ca2+ for reactivation. By pretreating cells before glycerination with colchicine, it is possible to study lamellipodial contraction independent of tail contraction. Similar responses to ATPγS pretreatment and unregulated myosin light chain kinase are observed in cells that only contain lamellipodia. SDS-PAGE electrophoresis of glycerinated fibroblasts incubated in ATPγ35S and Ca2+ shows that only two major proteins are thiophosphorylated, and that one of them, a band that comigrates with the 20K MW light chain of myosin, is thiophosphorylated in a Ca2+-dependent manner. Since the rate of tail contraction is several-fold faster after Ca2+ and ATPγS pretreatment or incubation in excess myosin light chain kinase, myosin light chain phosphorylation may be a rate-limiting step during contraction.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060612
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  • 12
    Electronic Resource
    Electronic Resource
    The use of submicroscopic gold particles combined with video contrast enhancement as a simple molecular probe for the living cell (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 105-113 
    Details
    ISSN: 0886-1544
    Keywords: video-microscopy ; colloidal gold ; immunocytochemistry ; microtubules ; receptors ; saltatory motion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We describe a new approach to probe the molecular biology of the living cell that uses small colloidal gold particles coupled to specific ligands. They are visualized in cells by bright-field, video enhanced contrast microscopy. We describe the basic aspects of the technique and provide examples of applications to intracellular motility, cell membrane dynamics, receptor translocation, internalization, and intracellular routing. We also provide examples of the use of this approach in immunospecific labelling of cells and tissue sections.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060207
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  • 13
    Electronic Resource
    Electronic Resource
    Incorporation and turnover of labeled exogenous tubulin in the mitotic spindles of Chaetopterus oocytes and HeLa cells (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 114-121 
    Details
    ISSN: 0886-1544
    Keywords: mitosis ; microtubules ; tubulin incorporation ; assembly polarity ; Chaetopterus ; HeLa cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The incorporation of tubulin into mitotic spindles in situ was studied by incubating permeabilized mitotic cells in solutions containing [3H]GTP-labeled or dichlorotriazinylamino fluorescein (DTAF)-labeled tubulin. Metaphase HeLa cells or spindle-containing “minicells” from Chaetopterus oocytes were lysed in a microtubule-assembly buffer plus 0.5% Nonidet P-40, 1 mg/ml 120,000g supernatant mammalian brain tubulin, and [3H]GTP. After different periods of incubation, mitotic spindles were isolated in 2 M-glycerol-containing assembly buffer and separated from unbound counts by centrifugation through a 4 M-glycerol cushion; 3H counts per mg protein increase linearly for 8-12 min and then reach a plateau or steady state in both Chaetopterus oocytes and HeLa cells. Addition of 4 mM CaCl2 blocks or reverses incorporation. Little or no [3H]GTP is incorporated if exogenous tubulin or lysed cells are omitted from the assembly mixture.To measure the loss rate of [3H]GTP-tubulin from mitotic spindles, cells were incubated in tubulin plus [3H]GTP for 30 min, and a 20-fold excess of cold GTP (2 mM) was added. Samples were removed after incubation for different periods, and spindles were isolated as described above and counted for 3H content. [3H]GTP is lost from spindles at a rate of about 16%/min until a new steady state is reached in about 8 min. These results are consistent with an incorporation and turnover of [3H]GTP-tubulin in spindle microtubules of these lysed-cell models.The location of this newly incorporated tubulin in the spindle was investigated by incorporating fluorescent DTAF-tubulin into mitotic spindles of these lysed cell types. A short pulse (2-5 min) appears to label microtubules (MTs) near metaphase chromosomes and longer exposures label the entire spindle.The rates of incorporation and turnover that we see by [3H]GTP and fluorescent tubulin incorporation in situ are faster than those observed with brain MTs at steady state in vitro but are in the range of the rates of spindle fiber formation in prophase, and spindle MT reassembly after cooling.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060208
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  • 14
    Electronic Resource
    Electronic Resource
    Towards a new classification of intracellular particle movements based on quantitative analyses (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 128-135 
    Details
    ISSN: 0886-1544
    Keywords: motion analysis ; axonal transport ; cytoplasmic transport ; Brownian motion ; AVEC-DIC microscopy ; saltatory particle motion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A survey study of organelle movements in a variety of cell types of plant and animal origin was made with the aid of video-enhanced contrast, differential interference contrast (AVEC-DIC) microscopy followed by fine analysis of the motile behavior of the individual organelles. We found that there exists besides Brownian motion a wide spectrum of active motions in cells, i.e. motion that is directionally biased through the expenditure of metabolic energy. The types of active motion seen range from a continuous motion (sometimes appearing as streaming) in plant cells and neurons to various types of less ordered and less well directed motion. We did not see any clear-cut qualitative difference between plant and animal cells or between systems presumed to be actin- and microtubule-based. A preliminary classification of the types of active motion is presented. The ongoing research activities, which aim at a more precise definition of the different types of motion by a set of quantitative parameters, are described, and the progress made so far is reported.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060210
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  • 15
    Electronic Resource
    Electronic Resource
    Polarized cytoplasmic movement and inhibition of saltations induced by calcium-mediated effects of microbeams in fungal hyphae (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 136-145 
    Details
    ISSN: 0886-1544
    Keywords: cytoplasmic movement ; microbeam ; Ca++ ; fungi ; saltatory movement ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have investigated the mechanisms that hyphae of the fungus Basidiobolus magnus use to accomplish bulk movement of their cytoplasm and saltatory organelle movements. When cells were irradiated with an ultraviolet microbeam, cytoplasmic contraction occurred. The posterior cytoplasm (toward the septum) always moved forward toward the irradiated area, whereas anterior cytoplasm (between the cell tip and target) never contracted back toward the site of irradiation. Thus, there is an intrinsic polarity in the cytoplasm. Irradiations also arrested saltatory movements. The effects of irradiation on both saltations and cytoplasmic movement appear to be mediated by Ca++. Chelating exogenous Ca++ before irradiation eliminated contractions and prevented the inhibition of saltations. Furthermore, the effects of irradiation could be duplicated by using the Ca++ ionophore A23187. We relate the present results to our previous report on the effects of irradiation on the cytoskeleton [McKerracher and Heath, 1986]. We conclude that two separate cytoskeletal networks exist in fungal cells, and that an actin-containing network generates bulk cytoplasmic movement.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060211
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  • 16
    Electronic Resource
    Electronic Resource
    In vitro movements of actin and myosin filaments from muscle (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 159-162 
    Details
    ISSN: 0886-1544
    Keywords: superprecipitation ; actomyosin ; F-actin bundle ; unidirectional sliding ; sliding velocity ; dark field microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Unidirectional sliding of myosin filaments along F-actin bundles was produced with purified muscle actin and myosin in the presence of ATP. The velocity of myosin filament sliding was independent of myosin filament length. This result supports a recent hypothesis that long distance movement of myosin cross-bridge can be induced by splitting of one ATP molecule [Yanagida, Arata, and Oosawa, 1985. Nature. 316:366-369; Higashi-Fujime. 1985. J. Cell Biol., 101:2335-2344].
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060214
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  • 17
    Electronic Resource
    Electronic Resource
    Structural evidence for contractile units in the giant smooth muscle cell of Beröe (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 153-158 
    Details
    ISSN: 0886-1544
    Keywords: giant smooth muscle fiber ; ctenophore ; myofilaments ; ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Bundles of giant smooth muscle fibers of the ctenophore Beröe have been stretched up to four times their initial length and then examined by transmission electron microscopy. Stretching induces the segregation of actin and thick (myosinlike) filaments into separate domains. The thick filaments domains are made of 20-30 filaments, with a regular spacing identical to that of nonstretched fibers. A moderate stretching permits the visualization of microtendons associating actin filament bundles to hyaluronidase-resistant condensations of the extracellular matrix. It is deduced from these observations that Beröe giant smooth muscle fibers possess myofibrils which attach at both ends upon the sarcolemmal membrane. Each myofibril is probably made of two long actin filament bundles (of approximately 150 filaments) and short (2-3 μm) myosinlike bundles (of approximately 30 filaments).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060213
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  • 18
    Electronic Resource
    Electronic Resource
    Motility and centrosomal organization during sea urchin and mouse fertilization (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 163-175 
    Details
    ISSN: 0886-1544
    Keywords: centrosomes ; fertilization ; mice ; microfilaments ; microtubules ; mitosis ; pericentriolar material ; sea urchins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Motility and the behavior and inheritance of centrosomes are investigated during mouse and sea urchin fertilization. Sperm incorporation in sea urchins requires microfilament activity in both sperm and eggs as tested with Latrunculin A, a novel inhibitor of microfilament assembly. In contrast the mouse spermhead is incorporated in the presence of microfilament inhibitors indicating an absence of microfilament activity at this stage. Pronuclear apposition is arrested by microfilament inhibitors in fertilized mouse oocytes. The migrations of the sperm and egg nuclei during sea urchin fertilization are dependent on microtubules organized into a radial monastral array, the sperm aster. Microtubule activity is also required during pronuclear apposition in the mouse egg, but they are organized by numerous egg cytoplasmic sites. By the use of an autoimmune antibody to centrosomal material, centrosomes are detected in sea urchin sperm but not in unfertilized eggs. The sea urchin centrosome expands and duplicates during first interphase and condenses to form the mitotic poles during division. Remarkably mouse sperm do not appear to have the centrosomal antigen and instead centrosomes are found in the unfertilized oocyte. These results indicate that both microfilaments and microtubules are required for the successful completion of fertilization in both sea urchins and mice, but at different stages. Furthermore they demonstrate that centrosomes are contributed by the sperm during sea urchin fertilization, but they might be maternally inherited in mammals.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060215
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  • 19
    Electronic Resource
    Electronic Resource
    Cell surface displacement during euglenoid movement and its computer simulation (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 186-192 
    Details
    ISSN: 0886-1544
    Keywords: Euglena ; pellicular strip ; cell shape ; sliding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We recently showed by videomicroscopy that adjacent pellicular strips slide relative to each other without contraction during S-shaped bending movement in Euglena fusca (Suzaki and Williamson, 1985). In order to validate this sliding strip mechanism for other species and other shape changes, a theoretical analysis and a computer simulation were carried out. Some of the commonly observed euglenoid cell shapes (rounded. S-shaped, and embryo-like shapes) were generated. Our results suggest that Euglena probably achieves a variety of cell shape changes by means of locally regulated sliding between adjacent pellicular strips of constant length and width.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060217
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  • 20
    Electronic Resource
    Electronic Resource
    Masthead (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986) 
    Details
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010101
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    Electronic Resource
    Electronic Resource
    Editorial (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 1-1 
    Details
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010102
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  • 22
    Electronic Resource
    Electronic Resource
    Comment: “Dry” enzymes (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 2-3 
    Details
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010103
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  • 23
    Electronic Resource
    Electronic Resource
    Proteins and peptides in water-restricted environments (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 4-15 
    Details
    ISSN: 0887-3585
    Keywords: membrane biomimetic system ; reverse micelles ; interfacial water ; myelin proteins ; solid enzyme activity ; organic solvents ; biotechnology ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010104
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  • 24
    Electronic Resource
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    The design, synthesis, and crystallization of an alpha-helical peptide (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 16-22 
    Details
    ISSN: 0887-3585
    Keywords: protein design ; alpha-helical bundle ; x-ray crystallography ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Twelve- and sixteen-residue peptides have been designed to form tetrameric alphahelical bundles. Both peptides are capable of folding into amphiphilic alpha-helices, with leucyl residues along one face and glutamyl and lysyl residues along the opposite face. Four such amphiphilic alpha-helices are capable of forming a noncovalently bonded tetramer. Neighboring helices run in antiparallel directions in the design, so that the complex has 222 symmetry. In the designed tetramer, the leucyl side chains interdigitate in the center in a hydrophobic interaction, and charged side chains are exposed to the solvent. The designed 12-mer(ALPHA-1) has been synthesized, and it forms helical aggregates in aqueous solution as judged by circular dichroic spectroscopy. It has also been crystallized and characterized by x-ray diffraction. The crystal symmetry is compatible with (but does not prove) the design. The design can be extended to a four-alpha-helical bundle formed from a single polypeptide by adding three peptide linkers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010105
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  • 25
    Electronic Resource
    Electronic Resource
    The design and production of semisynthetic ribonucleases with increased thermostability by incorporation of S-peptide analogues with enhanced helical stability (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 23-33 
    Details
    ISSN: 0887-3585
    Keywords: peptide helix ; protein stability ; framework model of folding ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Recent work has shown that, with synthetic analogues of C-peptide (residues 1-13 of ribonuclease A), the stability of the peptide helix in H2O depends strongly on the charge on the N-terminal residue. We have asked whether, in semisynthetic ribonuclease S reconstituted from S-protein plus an analogue of S-peptide (1-15), the stability of the peptide helix is correlated with the Tm of the reconstituted ribonuclease S. Six peptides have been made, which contain Glu9 → Leu, a blocked α-COO- group (—CONH2), and either Gln11 or Glu11. The N-terminal residue has been varied; its charge varies from +2 (Lys) to -1 (succinyl-Ala). We have measured the stability of the peptide helix, the affinity of the peptide for S-protein (by C.D. titration), and the thermal stability of the reconstituted ribonuclease S.All six peptide analogues show strongly enhanced helix formation compared to either S-peptide (1-15) or (1-19), and the helix content increases as the charge on the N-terminal residue changes from +2 to -1. All six peptides show increased affinity for S-protein compared to S-peptide (1-19), and all six reconstituted ribonucleases S show an increase in Tm compared to the protein with S-peptide (1-19). The Tm increases as the charge on residue 1 changes from +2 to -1. The largest increment in Tm is 6°.The results suggest that the stability of a protein can be increased by enhancing the stability of its secondary structure.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010106
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  • 26
    Electronic Resource
    Electronic Resource
    Stabilization of λ repressor against thermal denaturation by site-directed Gly→Ala changes in α-helix 3 (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 43-46 
    Details
    ISSN: 0887-3585
    Keywords: protein stability ; helix-coil ; mutant ; calorimetry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Oligonucleotide-directed mutagenesis has been used to replace α-helical glycines in the N-terminal domain of λ repressor with alanines. Since alanine is a significantly better helix-forming residue than glycine, these changes were predicted to have a stabilizing effect. We show that the Gly46→Ala substitution, the Gly48→Ala substitution, and the double substitution increase the melting temperature of the N-terminal domain by 3-6°.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010108
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  • 27
    Electronic Resource
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    Protein folding kinetics by combined use of rapid mixing techniques and NMR observation of individual amide protons (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 34-42 
    Details
    ISSN: 0887-3585
    Keywords: hydrogen exchange ; BPTI ; folding pathway ; protein dynamics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A method to be used for experimental studies of protein folding introduced by Schmid and Baldwin (J. Mol. Biol. 135: 199-215, 1979), which is based on the competition between amide hydrogen exchange and protein refolding, was extended by using rapid mixing techniques and 1H NMR to provide site-resolved kinetic information on the early phases of protein structure acquisition. In this method, a protonated solution of the unfolded protein is rapidly mixed with a deuterated buffer solution at conditions assuring protein refolding in the mixture. This simultaneously initates the exchange of unprotected amide protons with solvent deuterium and the refolding of protein segments which can protect amide groups from further exchange. After variable reaction times the amide proton exchange is quenched while folding to the native form continues to completion. By using 1H NMR, the extent of exchange at individual amide sites is then measured in the refolded protein. Competition experiments at variable reaction times or variable pH indicate the time at which each amide group is protected in the refolding process. This technique was applied to the basic pancreatic trypsin inhibitor, for which sequence-specific assignments of the amide proton NMR lines had previously been obtained. For eight individual amide protons located in the β-sheet and the C-terminal α-helix of this protein, apparent refolding rates in the range from 15s-1 to 60 s-1 were observed. These rates are on the time scale of the fast folding phase observed with optical probes.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010107
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  • 28
    Electronic Resource
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    Focusing of electric fields in the active site of Cu-Zn superoxide dismutase: Effects of ionic strength and amino-acid modification (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 47-59 
    Details
    ISSN: 0887-3585
    Keywords: protein electrostatics ; substrate diffusion ; Poisson-Boltzmann ; electrostatic potentials ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In this paper we report the implementation of a finite-difference algorithm which solves the linearized Poisson-Boltzmann equation for molecules of arbitrary shape and charge distribution and which includes the screening effects of electrolytes. The microcoding of the algorithm on an ST-100 array processor allows us to obtain electrostatic potential maps in and around a protein, including the effects of ionic strength, in about 30 minutes. We have applied the algorithm to a dimer of the protein Cu-Zn superoxide dismutase (SOD) and compared our results to those obtained from uniform dielectric models based on coulombic potentials. We find that both the shape of the protein-solvent boundary and the ionic strength of the solvent have a profound effect on the potentials in the solvent. For the case of SOD, the cluster of positive charge at the bottom of the active site channel produces a strongly enhanced positive potential due to the focusing of field lines in the channel - a result that cannot be obtained with any uniform dielectric model. The remainder of the protein is surrounded by a weak negative potential. The electrostatic potential of the enzyme seems designed to provide a large cross-sectional area for productive collisions. Based on the ionic strength dependence of the size of the positive potential region emanating from the active site and the repulsive negative potential barrier surrounding the protein, we are able to suggest an explanation for the ionic strength dependence of the activity of the native and chemically modified forms of the enzyme.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010109
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  • 29
    Electronic Resource
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    A domain of the klenow fragment of Escherichia coli DNA polymerase I has polymerase but no exonuclease activity (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 66-73 
    Details
    ISSN: 0887-3585
    Keywords: protein domain ; polymerase ; 3′-5′ exonuclease ; artificial gene ; expression vector ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The Klenow fragment of DNA polymerase I from Escherichia coli has two enzymatic activities: DNA polymerase and 3′-5′ exonuclease. The crystal structure showed that the fragment is folded into two distinct domains. The smaller domain has a binding site for deoxynucleoside monophosphate and a divalent metal ion that is thought to identify the 3′-5′ exonuclease active site. The larger C-terminal domain contains a deep cleft that is believed to bind duplex DNA. Several lines of evidence suggested that the large domain also contains the polymerase active site. To test this hypothesis, we have cloned the DNA coding for the large domain into an expression system and purified the protein product. We find that the C-terminal domain has polymerase activity (albeit at a lower specific activity than the native Klenow fragment) but no measurable 3′-5′ exonuclease activity. These data are consistent with the hypothesis that each of the three enzymatic activities of DNA polymerase I from E. coli resides on a separate protein structural domain.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010111
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  • 30
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    PseqIP: A nonredundant and exhaustive protein sequence data bank generated from 4 major existing collections (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 60-65 
    Details
    ISSN: 0887-3585
    Keywords: computerized data bank ; sequence comparison heuristics ; databank access ; data bank merging ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Four major protein sequence data collections (NBRF-PIR, PSD-Kyoto, PGtrans, and NEWAT) have been merged into a single nonredundant data bank called PseqIP. The data bank entries were automatically matched by a heuristic computer program relying on the fast computation of the number of tetrapeptides shared by two sequences. PseqIP 1.0 includes 6,068 different protein sequences for a total of 1,357,067 residues, representing most of the available sequence information to date. During the course of this work, we found about 600 occurrences course of a protein sequence recorded with a one-amino-acid variation in at least two different data banks. A flat file (ASCII computer-readable format) version of PseqIP 1.0, well-suited for exhaustive homology searches and statistical sequence analysis, is available from our laboratory.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010110
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  • 31
    Electronic Resource
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    The galactan-binding immunoglobulin Fab J539: An x-ray diffraction study at 2.6-Å resolution (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 74-80 
    Details
    ISSN: 0887-3585
    Keywords: antibody ; crystal structure ; anti-galactan ; J539 ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The crystal structure of the Fab of the galactan-binding immunoglobulin J539 (a mouse IgA,κ) has been determined at a resolution of approximately 2.6 Å by X-ray diffraction. The starting model was that obtained from the real space search described previously (Navia, M.A., Segal, D.M., Padlan, E.A., Davies, D.R., Rao, D.N., Rudikoff, S. and Potter, M. “Crystal structure of galactan-binding mouse immunoglobulin J539 Fab at 4.5 Å resolution.” Proc. Nat. Acad. Sci. USA, 76:4071-4074, 1979). This Fab structure has now been refined by restrained least-squares procedures to an R-value of 19% for the 11,690 unique reflections between 8.0 Å and 2.6 Å. The rms deviation from ideal bond lengths is 0.025 Å. The overall structure differs from McPC603 Fab, another mouse IgA,κ antibody, in that the elbow bend, relating the variable and constant parts of the molecule, is 145° vs. 133° for McPC603. The region of the molecule expected to be the antigen binding site contains a large cavity with two clefts leading away from it. This has been fitted with a model of an oligo-galactan.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010112
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  • 32
    Electronic Resource
    Electronic Resource
    Reciprocal control of retinal rod cyclic GMP phosphodiesterase by its γ subunit and transducin (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 90-99 
    Details
    ISSN: 0887-3585
    Keywords: visual excitation ; rhodopsin ; enzyme regulation ; cyclic nucleotide cascade ; G-proteins ; inhibitory subunit ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The switching on of the cGMP phosphodiesterase (PDE) in retinal rod outer segments by activated transducin (Tα-GTP) is a key step invisual excitation. The finding that trypsin activates PDE (αβγ) by degrading its γ subunit and the reversal of this activation by γ led to the proposal that Tα-GTP activates PDE by relieving an inhibitory constraint imposed by γ (Hurley and Stryer: J. Biol. Chem. 257:11094-11099, 1982). We report here studies showing that the addition of γ subunit also reverses the activation of PDE by Tα-GTP-γS. A procedure for preparing γ in high yield (50-80%) is presented. Analyses of SDS polyacrylamide gel slices confirmed that inhibitorya activity resides in the γ subunit. Nanomolar γ blocks the activation of PDE by micromolar Tα-GTPγS. The degree of activation of PDE depends reciprocally on the concentrations of γ and Tα-GTPγS. γ remains bound to the disk membrane during the activation of PDE by transducin. The binding of γ to the αβ subunits of native PDE is very tight; the dissociation constant is less than 10 pM, indicating that fewer than 1 in 1,700 PDE molecules in rod outer segments are activated in the absence of Tα-GTP.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010114
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  • 33
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    Mutant forms of staphylococcal nuclease with altered patterns of guanidine hydrochloride and urea denaturation (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 81-89 
    Details
    ISSN: 0887-3585
    Keywords: protein stability ; protein denaturation ; denatured state ; structural intermediates ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Eleven mutant forms of staphylococcal nuclease with one or more defined amino acid substitutions have been analyzed by solvent denaturation by using intrinsic fluorescence to follow the denaturation reaction. On the basis of patterns observed in the value of m-the rate of change of log Kapp (the apparent equilibrium constant between the native and denatured states) with denaturant concentration - these proteins can be grouped into two classes. For class I mutants, the value of m with guanidine hydrochloride is less than the wild-type value and is either constant or increases slightly with increasing denaturant; the value of m with urea is also less than wild type but shows a marked increase with increasing denaturant concentration, often approaching but never exceeding the wild-type value. For class II mutants, m is constant and is greater than wild type in both denaturants, with the increase being consistently larger in guanidine hydrochloride than in urea. When double or triple mutants are constructed from members of the same mutant class, the change in m is usually the sum of the changes produced by each mutation in isolation. One plausible explanation for these altered patterns of denaturation is that chain-chain or chain-solvent interactions in the denatured state have been modified - interactions which appear to involve hydrophobic groups.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010113
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  • 34
    Electronic Resource
    Electronic Resource
    Masthead (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986) 
    Details
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010201
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  • 35
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    A novel method for selective isolation of C-terminal peptides from tryptic digests of proteins by immobilized anhydrotrypsin: Application to structural analyses of the tail sheath and tube proteins from bacteriophage T4 (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 100-107 
    Details
    ISSN: 0887-3585
    Keywords: affinity chromatography ; high-performance liquid chromatography ; bacteriophage T4 tail sheath protein ; bacteriophage T4 tail tube protein ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A novel method useful for selective isolation of the C-terminal peptide from a tryptic digestion mixture of a protein has been developed by taking advantage of a unique property of anhydrotrypsin, which has a strong specific affinity for the peptides containing arginine or lysine at their C-termini. Briefly, peptides produced by tryptic digestion of a protein are fractionated by affinity chromatography on a column of immobilized anhydrotrypsin. The C-terminal peptide is recovered in a breakthrough fraction, which the remainders are adsorbed on the column (unless the protein ends in arginine or lysine). The breakthrough fraction is then subjected to reversed-phase high-perfomance liquid chromatography in order to purify the C-terminal peptide. Using this method, we have successfully isolated the C-terminal peptides from tryptic digests of the sheath protein (gp 18) and the tube protein (gp 19) of bacteriophage T4. The analytical results on these peptides, together with the information on the N-terminal structures of the original proteins and on the nucleotide sequences of genes 18 and 19, allowed us to establish the complete primary structures of the two proteins.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010115
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  • 36
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    Protein fluorescence quenching by small molecules: Protein penetration versus solvent exposure (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 109-115 
    Details
    ISSN: 0887-3585
    Keywords: proteins ; protein dynamics ; tryptophan exposure ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Experiments were done to test the thesis that acrylamide and similar small molecules can penetrate into proteins on a nanosecond time scale. The approach taken was to measure the pattern of fluorescence quenching exhibited by quenching molecules differing in molecular character (size, polarity, charge) when these are directed against protein tryptophans that cover the whole range of tryptophan accesibility. If quenching involves protein penetration and internal quencher migration, one expects that larger quenchers and more polar quenchers should display lesser quenching. In fact, no significant dependence on quencher character was found. For proteins that display measurable quenching, the disparate quenchers studied display very similar quenching rate constants when directed against any particular protein tryptophan. For several proteins having tryptophans known to be buried, no quenching occurs. These results are not consistent with the view that the kinds of small molecules studied can quite generally penetrate into and diffuse about within proteins at near-diffusion-limited rates. Rather the results suggest that when quenching is observed, the pathway involves encounters with tryptophans that are partially exposed at the protein surface. Available crystallographic results support this conclusion.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010202
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  • 37
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    Translational repression in vitro by the bacteriophage T4 regA protein (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 116-124 
    Details
    ISSN: 0887-3585
    Keywords: translational repressor ; in vitro transcription-translation ; gene expression ; protein purification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The bacteriophage T4 translational represor regA protein has been purified from an overproducing strain, and its activity has been studied in simple in vitro protein synthesis reactions. RegA protein was found to inhibit the translation of T4 genes 44, 45, and ORF45-1 in a concentration-dependent fashion. Expression of two other T4 genes which are insensitive to regA protein in vivo, genes 32 and 43, was unaffected by the presence of regA protein. Specific inhibition of synthesis of genes 44, 45, and ORF 45-1 proteins was achieved with 5-20 μM concentrations of regA protein, without the addition of any other T4 encoded proteins or cofactors. When in vitro protein synthesis was performed in two steps, uncoupling translation from transcription, regA protein had an inhibitory effect regardless of whether it was added at the initiation of transcription or only at the translation step. This indicates that regA protein functions during the translation step of protein synthesis in vitro in agreement with previous in vivo studies of regA protein.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010203
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  • 38
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    Cloning, expression, and nucleotide sequence of livR, the repressor for high-affinity branched-chain amino acid transport in Escherichia coli (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 125-133 
    Details
    ISSN: 0887-3585
    Keywords: regulation ; prokaryotic bacteria ; leucine uptake ; leucyl tRNA corepressor ; cell physiology ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The livR gene encoding the repressor for high-affinity branched-chain amino acid transport in Escherichia coli has been cloned from a library prepared from the episome F106. The inserted DNA fragment from the initial cloned plasmid, pANT1, complemented two independent, spontaneously derived, regulatory mutations. Subcloning as well as the creation of deletions with Bal31 exonuclease revealed that the entire regulatory region is contained within a 1.1-kb RsaI-SalI fragment. Expression of the pANT plasmids in E. coli minicells showed that the regulatory region encodes one detectable protein with an apparent molecular weight of 21,000. DNA sequencing revealed one open reading frame of 501 bp encoding a protein with a calculated MW of 19,155. The potential secondary structure of the regulatory protein has been predicted and it suggests that the carboxy terminus may fold into three consecutive alpha helices. These results suggests that the livR gene encodes a repressor which plays a role in the regulation of expression of the livJ and the livK transport genes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010204
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  • 39
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    Peptide and ester synthesis in organic solvents catalyzed by seryl proteases linked to alumina (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 134-138 
    Details
    ISSN: 0887-3585
    Keywords: enzymatic transesterification ; peptide synthesis ; trypsin ; chymotrypsin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Trypsin and α-chymotrypsin were immobilized to alumina-phosphocolamine complex, activated by glutaraldehyde. The immobilized enzymes show a great stability toward organic solvents miscible or immiscible with water. In the presence of a low concentration of water, the immobilized enzymes catalyzed transesterification reactions as well as peptide synthesis. The synthesized peptides were stable toward the immobilized enzymes.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010205
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  • 40
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    Isolation and characterization of native human renin derived from Chinese hamster ovary cells (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 139-145 
    Details
    ISSN: 0887-3585
    Keywords: hypertension ; renin production ; mammalian expression ; affinity chromatography ; genetic engineering ; prorenin secretion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Transfection of Chinese hamster ovary (CHO) cells with a plasmid containing the cDNA for human preprorenin has provided cell lines that secrete 15 mg of native prorenin per liter of culture medium. Tryptic activation of the prorenin occurs by selective cleavage of the Arg66-Leu67 bond (numbering as in preprorenin). The renin product, purified in a single step and in high yield by affinity chromatography, is fully stable for as long as 8 months when stored in solution at 4°C and pH 6.5. Purity of the renin was judged to be greater than 95% by gel electrophoresis, compositional and N-terminal sequence analyses, and specific enzyme activity. An important aspect of the present work is the development of a direct assay for renin which permits accurate and reproducible evaluation of enzyme units and kinetic parameters. Application of methods described herein, combined with appropriate scale-up fermentation capabilities, provides the means for generating gram quantities of human renin and its zymogen.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010206
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  • 41
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    An algorithm for determining the conformation of polypeptide segments in proteins by systematic search (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 146-163 
    Details
    ISSN: 0887-3585
    Keywords: protein conformation ; energy calculations ; protein modeling ; loop conformation ; surface area ; homologous proteins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The feasibility of determining the conformation of segments of polypeptide chain up to six residues in length in globular proteins by means of systematic search through the possibles conformations has been investigated. Trial conformations are generated by using representative sets of φ, ψ, and χ angels that have been derived from an examination of the distributions of these angles in refined protein structures. A set of filters based on simple rules that protein structures obey is used to reduce the number of conformations to a manageable total. The most important filters are the maintenance of chain integrity and the avoidance of tooshort van der Waals contacts with the rest of the protein and with other portions of the segment under construction. The procedure is intended to be used with approximate models so that allowance is made throughout for errors in the rest of the structure. All possible main chains are first constructed and then all possible side-chain conformations are built onto each of these. The electrostatic energy, including a solvent screening term, and the exposed hyrophobic area are evaluated for each accepted conformation. The method has been tested on two segments of chain in the trypsin like enzyme from Streptomyces griseus. It is found that there is a wide spread of energies among the accepted conformations, and the lowest energy ones have satisfactorily small root mean square deviations from the X-ray structure.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010207
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    pH Dependence of 2,3-diphosphoglycerate binding to human hemoglobin Ao at 21.5°C (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 164-175 
    Details
    ISSN: 0887-3585
    Keywords: DPG ; organophosphates ; ligand interactions ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Rate equilibrium dialysis was used to measure the binding of 2,3-diphosphoglycerate (DPG) to human oxy- and deoxyhemoglobin AO over the range pH 5-9, at 21.5°C. This approach yielded an accurate, precise, and self-consistent set of model-independent association constants. These data were successfully fitted to a thermodynamic model which is fuctionally similar to a Hill equation. The isotherms generated by this fitting procedure appear to intersect at low pH and converge at high pH. This apparent convergence at high pH is consistent with results obtained by oxygen equilibria studies performed under conditions of saturating DPG. These calculated isotherms were used to determine the enhancement of the Bohr effect as a function of pH. These results are consistent with data obtained by pH stat measurements by other investigators.This paper presents the first in a series of studies that will provide a systematic characterization of the interaction between hemoglobin and DPG.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010208
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    The restoration of electron micrographs blurred by drift and rotation (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 176-187 
    Details
    ISSN: 0887-3585
    Keywords: drifted micrographs ; rotational blur ; thin sections ; Wiener filtering ; image analysis ; sickle hemoglobin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We have investigated the restoration of electron micrographs exhibiting blurring due to drift and rotation. Blurring due to drift arises in micrographs taken of a specimen which is moving relative to the image plane. A related problem is that of rotational blurring which arises in micrographs of thin sections of helical particles viewed in cross section. The twist of the particle within the finite thickness of the section causes the image to appear rotationally blurred about the helical axis.Restoration algorithms were evaluated by applying them to the restoration of blurred model images degraded by additive Gaussian noise. Model images were also used to investigate how an incorrect estimate of the point spread function function describing the blur would effect the restoration. Images were, if necessary, geometrically transformed to a space in which the point spread function of the blur can be considered as linear and space invariant as, under these conditions, the restoration algorithms are greatly simplified. In the case of the rotationally blurred images this procedur was accomplished by transforming the image to polar coordinates.The restoration techniques were successfully applied to blurred micrographs of bacteriophage T4 and crystals of catalase. The quality of the restoration was judged by comparisons of the restored images to undegraded images. Application to micrographs of rotationally blurred cross sections of helical macrofibers of sickle hemoglobin resulted in a reduction in the amount of rotational blurring.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010209
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    Activation of retinal rod cyclic GMP-phosphodiesterase by transducin: Characterization of the complex formed by phosphodiesterase inhibitor and transducin α-subunit (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 188-193 
    Details
    ISSN: 0887-3585
    Keywords: G-protein ; phototransduction ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The GTP-binding subunit of transducin (Tα) activates the cGMP phosphodiesterase (PDE) of bovine retinal rods by relieving the constraint imposed by the inhibitory subunit PDEγ. We have isolated and characterized the complex Tα.GTPγS-PDEγ formed when Tα is activated by the nonhydrolyzable analog GTPγS. Sedimentation and light-scattering techniques demonstrate that, in contrast to free Tγ.GTPγS, which is soluble, the Tα.GTPγS-PDEγ complex, as well as Tα.GTP-PDEγ, is membrane bound at cytosolic ionic strength. It is eluted from the membrane at low ionic strength as a monomeric and 1:1 stoichiometric complex. The relative affinities of PDEγ for PDEαβ and for Tα.GTP are discussed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010210
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    Electronic Resource
    Masthead (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986) 
    Details
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010301
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  • 46
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    Set of novel, conserved proteins fold pre-messenger RNA into ribonucleosomes (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 195-210 
    Details
    ISSN: 0887-3585
    Keywords: protein domains ; oligomeric assembly ; RNA splicing ; multiple binding sites ; RNP core proteins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010302
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    Stabilization of the ribonuclease S-peptide α-helix by trifluoroethanol (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 211-217 
    Details
    ISSN: 0887-3585
    Keywords: protein folding ; α-helix stabilization ; peptide structural stability ; circular dichroism ; protein electrostatics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The effects of trifluoroethanol (TFE) on the stability of the α-helix formed by ribonuclease S-peptide, residues 1-19 of ribonuclease A, were studied by measuring circular dichroism as a function of TFE concentration, pH, and temperature. The S-peptide forms an unusually stable α-helix, which is known to be stabilized by TFE. The magnitude of the effect of charged groups on the peptide, manifested by the change in α-helix stability as a function of pH, was not altered significantly by either TFE concentration or temperature, indicating that the lower dielectric constant of TFE is not important in the stabilization of this α-helix. This suggests that the α-helix might be stabilized by many interactions in addition to the effects of charges. The titration curve of circular dichroism vs. TFE concentration appears to be cooperative at 0°C, but becomes progressively less cooperative at temperatures between 25 and 75°C. The properties of the TFE stabilization indicate that TFE might be a useful probe with which to measure the stability of marginally stable peptides and small proteins.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010303
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    The DNA replication inhibitor microcin B17 is a forty-three-amino-acid protein containing sixty percent glycine (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 230-238 
    Details
    ISSN: 0887-3585
    Keywords: microcins ; peptide antibiotic ; protein processing ; HPLC ; protein secretion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Microcin B17 is a low-molecular-weight protein that inhibits DNA replication in a number of enteric bacteria. It is produced by bacterial strains which harbor a 70-kilobase plasmid called pMccB17. Four plasmid genes (named mcbABCD) are required for its production. The product of the mcbA gene was identified by labelling minicells. The mcbA gene product was slightly larger when a mutation in any of the other three production genes was present. This indicates that these genes are involved in processing the primary mcbA product to yield the active molecule. The mcbA gene product predicted from the nucleotide sequence has 69 amino acids including 28 glycine residues. Microcin B17 was extracted from the cells by boiling in 100 mM acetic acid, 1 mM EDTA, and purified to homogeneity in a single step by high-performance liquid chromatography through a C18 column. The N-terminal amino acid sequence and amino acid composition demonstrated that mcbA is the structural gene for microcin B17. The active molecule is a processed product lacking the first 26 N-terminal residues. The 43 remaining residues include 26 glycines. While microcin B17 is an exported protein, the cleaved N-terminal peptide does not have the characteristic properties of a “signal sequence,” which suggests that it is secreted by a mechanism different from that used by most secreted proteins of E. coli.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010305
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    Properties of a second sensory receptor protein in Halobacterium halobium phototaxis (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 239-246 
    Details
    ISSN: 0887-3585
    Keywords: halobacteria ; photosensory receptor ; retinal ; slow-cycling rhodopsins ; sensory rhodopsins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A second slow-cycling retinylidene protein, in addition to slow-cycling (sensory) rhodopsin (SR), can be bleached with hydroxylamine and regenerated with all-trans retinal in photosensory signaling Halobacterium halobium membranes. Flash photolysis shows this protein undergoes a photochemical reaction cycle characterized by photoconversion of its ground state (λmax 480 nm) to a species with λmax ≤ 360 nm, which thermally regenerates the 480-nm species with a t½ of 260 msec at 25°C, under conditions in which SR photocycles at 650 msec in the same membranes. Mutants characterized with respect to their phototaxis behavior are identified which contain SR and the 480-nm pigment, the latter ranging from undetectable to a concentration equal to that of SR. Receptor mutants lacking all phototaxis sensitivity lack both of the photochemically reactive proteins. The mutant properties contribute to an accumulation of behavioral and spectroscopic evidence that the 480-nm pigment is a second sensory photoreceptor in H. halobium. NaDodSO4-polyacrylamide gel electrophoresis of [3H]retinal-labeled membrane proteins from the mutants indicates SR and the 480-nm pigment contain distinct chromophoric polypeptides differing in their migration rates. The data implicate polypeptides of 25,000 Mr and 23,000 Mr as retinal-binding polypeptides of SR and the 480-nm protein, respectively.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010306
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    A very short peptide makes a voltage-dependent ion channel: The critical length of the channel domain of colicin E1 (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 218-229 
    Details
    ISSN: 0887-3585
    Keywords: colicin E1 ; site-directed mutagenesis ; ion channel ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cleavage of colicin E1 molecules with a variety of proteases or with cyanogen bromide (CNBr) generates COOH-terminal fragments which have channel-forming activity similar to that of intact colicin in planar lipid bilayer membranes. The smallest channel-forming fragment obtained by CNBr cleavage of the wild-type molecule consists of the C-terminal 152 amino acids. By the use of oligonucleotide-directed mutagenesis, we have made nine mutants along this 152 amino acid peptide, in which an amino acid was replaced by methionine in order to create a new CNBr cleavage site. The smallest of the CNBr-cleaved C-terminal fragments with channel-forming activity, in planar bilayer membranes, was generated by cleavage at new Met position 428 and has 94 amino acids, whereas a 75 amino acid peptide produced by cleavage of a new Met at position 447 did not have channel activity. The NH2-terminus of the channel-forming domain of colicin E1 appears therfore to lie between residues 428 and 447. Since, however, the last six C-terminal residues of the colicin can be removed without changing activity, the number of amino acids necessary to form the channel is 88 or less. In addition, the unique Cys residue in colicin E1 was replaced by Gly, and nine mutants were then made with Cys placed at sequential locations along the peptide for eventual use as sulfhydryl attachment sites to determine the local environment of the replaced amino acid. In the course of making 21 mutants, eight charged residues have been replaced by uncharged Met or Cys without changing the biological activity of the intact molecule.It has been proposed previously that the conformation of the colicin E1 channel is a barrel formed from five or six α-helices, each having 20 amino acids spanning the membrane and two to four residues making the turn at the boundary of the membrane. Our finding that 88 amino acids can make an active channel, combined with recently reported stoichiometric evidence that the channel is a monomer excludes this model and adds significant constraints which can be used in building a molecular model of the channel.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010304
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    Kinetic characterization of early intermediates in the folding of E. coli tryptophan-synthase β2 subunit (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 247-255 
    Details
    ISSN: 0887-3585
    Keywords: protein folding ; domain interactions ; fluorescence transfer ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This report describes the use of fluorescence energy transfer between an intrinsic energy donor (tryptophan 177) and two chemically added acceptors to study intermediates in the folding of the β2 subunit of E. coli tryptophan-synthase. Two early folding steps are thus identified and characterized. One is very rapid (its rate constant at 12°C is 0.02 sec-1) and corresponds to the folding of the N-terminal domain into a structure whose overall features approximate well those of the native domain. The second step is somewhat slower (its rate constant at 12°C is 0.008 sec-1) and involves a conformational rearrangement of the N-terminal domain brought about by the interactions between the N-and C-terminal domains within a monomeric β chain. This brings to five the number of intermediates which have been identified and ordered on the folding pathway of the dimeric β2 subunit.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010307
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    Preliminary x-ray diffraction analysis of HhaII endonuclease-DNA cocrystals (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 263-266 
    Details
    ISSN: 0887-3585
    Keywords: protein-DNA interaction ; overproducer clone ; sequence-specific recognition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: HhaII restriction endonuclease purified from an overproducing recombinant E. coli clone has been cocrystallized with a heptanucleotide duplex, d-GGAGTCC:GGACTCC. The cocrystals are monoclonic and belong to the space group C2. The unit cell dimensions are a = 199.0±1.0 Å, b = 100.0±0.5 Å, c = 80.3±0.4 Å, and β = 101.0±1.0°. There appear to be two dimers per asymmetric unit and the crystals diffract to 4-Å resolution.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010309
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    Calculating three-dimensional changes in protein structure due to amino-acid substitutions: The variable region of immunoglobulins (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 267-279 
    Details
    ISSN: 0887-3585
    Keywords: molecular model building ; energy minimization ; homology modeling ; site-specific mutagenesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A procedure (coupled perturbation procedure, CPP) is introduced as a specific method for calculating the detailed three-dimensional structure of a protein molecule which has a nummber of amino-acid substitutions relative to some previously determined “parent” protein structure. The accuracy of the procedure is tested by calculating the conformation of a region of the human immunoglobulin fragment Fab Kol based on the analogous region of the human immunoglobulin fragment Fab New. Both structures have previously been determined crystallographically. The calculated model is accurate to the extent that both of the sequence differences in the region are modeled correctly and that conformational changes in a number of nearby residues are correctly identified. CPP is shown to give better results than other commonly used modeling procedures when applied to the same problem.
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    URL: http://dx.doi.org/10.1002/prot.340010310
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    Proteolytic dissection of a hapten binding site (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 256-262 
    Details
    ISSN: 0887-3585
    Keywords: FV fragment ; space filling hapten ; reconstitution ; scratched analysis ; equilibrium dialysis ; contact residues ; hypervariable loops ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: IgG Gar, a human myeloma protein that binds riboflavin with a high affinity, was used to derive variable region fragments from the heavy chain and the light chain. Riboflavin binding ability of the active site generated by V(H) and light chain and the active site generated by V(H) and V(L) was compared to riboflavin binding by the F(ab) fragment. The riboflavin binding ability of the F(ab) fragment is the same as the intact molecule, while the binding ability of the active site formed by V(H) and light chain is lowered by two to three orders of magnitude, indicating that the removal of C(H1) domain decreases the interaction between riboflavin and the amino acids that is important in tight binding of riboflavin. Removal of the third hypervariable region and the constant region domain from the light chain further lowers the binding constant by one order of magnitude. The results indicate that the V(H) and V(L) segments of IgG Gar can reconstitute a riboflavin binding site. The decrease in affinity probably reflects a decrease in the rigidity with which the hypervariable loops are held together to place the contact amino acid residues in optimal contact with the hapten.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010308
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    Affinity of nonhomologous amphiphilic peptides toward a monoclonal antibody raised against apolipoprotein A-I (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 280-286 
    Details
    ISSN: 0887-3585
    Keywords: antibody affinity ; ELISA ; β-endorphin models ; melittin model ; amphiphilic α-helix ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Monoclonal antibodies against human apolipoprotein A-I (apoA-I) were generated by the hybridoma technique. Clone G-10 was selected on the basis of its highest titer. The affinity of this antibody toward a series of synthetic peptides differing in length, amino acid composition, and amphiphilicity was tested by using both the indirect and the competitive enzyme-linked immunosorbent techniques (ELISA). From these measurements we calculated dissociation constants of the complexes of the antibody with apoA-I bound to the surface of the microtiter plate, apoA-I in solution, and any of the several peptides in solution. The dissociation constant (Kd) of the immobilized apoA-I/anti-apoA-I-complex, Kd = 2 × 10-9 M, was significantly lower than that of the complex resulting from the interaction between anti-apoA-I and either apoA-I in solution or any of the several amphiphilic helical peptides in solution. Peptides devoid of amphiphilic secondary structure were inert. These data are consistent with the proposal that monoclonal G-10 recognizes in antigenic peptides an α-helical secondary structure of defined hydrophilic-lipophilic balance and comparatively less the specific amino acid side chains. We propose that the highest contribution to the free energy of binding (8 Kcal/mole) is derived from the docking of the helix to the antibody. It follows that in probing the specificity of a monoclonal antibody the conformation and the physical environment of the interacting antigen must be taken into account.
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    URL: http://dx.doi.org/10.1002/prot.340010311
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  • 56
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    Masthead (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986) 
    Details
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010401
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    Editorial (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. i 
    Details
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010402
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    Isolation and analysis of arc repressor mutants: Evidence for an unusual mechanism of DNA binding (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 302-311 
    Details
    ISSN: 0887-3585
    Keywords: mutant proteins ; protein stability ; operator binding ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We have isolated 64 different missense mutations at 36 out of 53 residue positions in the Arc repressor of bacteriophage P22. Many of the mutant proteins with substitutions in the C-terminal 40 residues of Arc have reduced intracellular levels and probably have altered structures or stabilities. Mutations in the N-terminal ten residues of Arc cause large decreases in operator DNA binding affinity without affecting the ability of Arc to fold into a stable three-dimensional structure. We argue that these N-terminal residues are important for operator recognition but that they are not part of a conventional helix-turn-helix DNA binding structure. These results suggest that Arc may use a new mechanism for sequence specific DNA binding.
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    URL: http://dx.doi.org/10.1002/prot.340010404
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    Molecular structure and evolution of adrenergic and cholinergic receptors (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 287-301 
    Details
    ISSN: 0887-3585
    Keywords: primary sequence homology ; primary structure ; secondary structure ; quaternary structure ; gene cloning ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010403
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    Primary structure of the reaction center from Rhodopseudomonas sphaeroides (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 312-325 
    Details
    ISSN: 0887-3585
    Keywords: membrane proteins ; nucleotide sequence ; evolution ; photosynthesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The reaction center is a pigmentprotein complex that mediates the initial photochemical steps of photosynthesis. The amino-terminai sequences of the L, M, and H subunits and the nucleotide and derived amino acid sequences of the L and M structural genes from Rhodopseudomonas sphaeroides have previously been determined. We report here the sequence of the H subunit, completing the primary structure determination of the reaction center from R. sphaeroides. The nucleotide sequence of the gene encoding the H subunit was determined by the dideoxy method after subcloning fragments into single-stranded M13 phage vectors. This information was used to derive the amino acid sequence of the corresponding polypeptide. The termini of the primary structure of the H subunit were established by means of the amino and carboxy terminal sequences of the polypeptide. The data showed that hte H subunit is composed of 260 residues, corresponding to a molecular weight of 28,003. A molecular weight of 100,858 for the reaction center was calculated from the primary structures of the subunits and the cofactors. Examination of the genes encoding the reaction center shows that the codon usage is strongly bviased towards codons ending in G and C. Hydropathy analysis of the H subunit sequence reveals one stretch opf hydrophobic residues near the amino terminus; the L and M subunits contain five such stretches. From a comparison of the sequences of homologous proteins found in bacterial reaction centers and photosystem II of plants, an evolutionary tree was contructed. The analysis of evolutionary relationships showed that the L and M subunits of reaction centers and D1 and D2 proteins of photosystem II are descended from a common ancestor, and that the rate of change in these proteins was much higher in the first billion years after the divergence of the reaction center and photosystem II than in the subsequent billion years represented by the divergence of the species containing these proteins.
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    URL: http://dx.doi.org/10.1002/prot.340010405
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    Sequence conservation and region shuffling in an endoglucanase and an exoglucanase from Cellulomonas fimi (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 335-341 
    Details
    ISSN: 0887-3585
    Keywords: cellulases ; active sites ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cellulomonas fimi produces an endoglucanase and an exoglucanase which bind strongly to cellulose. Each enzyme contains three distinct regions: a short sequence of about 20 amino acids containing only proline and threonine (the ProThr box); an irregular region, rich in hydroxyamino acids, of low charge density, and which is predicted to have little secondary structure; and an ordered region of higher charge density which contains a potential active site, and which is predicted to have secondary structure; and an ordered region of higher charge density which contains a potential active site, and which is predicted to have secondary structure. The Pro-Thr box is conserved almost perfectly in the two enzymes. The irregular regions are 50% conserved, and the conserved sequences include four Asn-Xaa-Ser/Thr sites. The ordered regions appear not to be conserved, but the potential active sites both have the sequence Glu-Xaa7-Asn-Xaa6-Thr; they occur at widely separated sites in the two regions. The order of the regions is reversed in the two enzymes: irregular-Pro-Thr box-ordered in the endoglucanase; ordered-Pro-Thr box irregular in the exoglucanase. The genes for the two enzymes appear to have arisen by shuffling of two conserved sequences and either one or two other sequences.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010407
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    Proteases of enhanced stability: Characteization of a thermostable variant of subtilisin (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 326-334 
    Details
    ISSN: 0887-3585
    Keywords: thermal stability ; protein engineering ; mutagenesis ; plate assay ; thermophilic enzymes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A Procedure has been developed for the isolation and identification of mutants in the bacterial serine protease subtilisin that exhibit enhanced thermal stability. The cloned subtilisin BPN'gene from Bacillus amyloliquefaciens was treated with bisulfite, a chemical mutagen that deaminates cytosine to uracil in single-stranded DNA. Strains containing the cloned, mutagenized subtilisin gene which produced subtilisin with enhanced thermal stability were selected by a simple plate assay procedure which screens for esterase activity on nitrocellulose filters after preincubation at elevated temperatures. One thermostable subtilisin variant, designated 7150, has been fully characterized and found to differ from wild-type subtilisin by a single substitution of Ser for Asn at position 218. The 7150 enzyme was found to undergo thermal inactivation at onefourth the rate of the wild-type enzyme when incubated at elevated temperatures. Moreover, the midpoint in the thermally induced transition from the folded to unfolded state was found to be 2.4-3.9°C higher for 7150 as determined by differential scanning calorimetry under a variety of conditions. The refined, 1.8-Å crystal structures of the wild-type and 7150 subtilisin have been compared in detail, leading to the conclusion that slight improvements in hydrogen bond parameters in the vicinity of position 218 result in the enhanced thermal stability of 7150.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010406
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    Predicting antibody hypervariable loop conformations II: Minimization and molecular dynamics studies of MCPC603 from many randomly generated loop conformations (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 342-362 
    Details
    ISSN: 0887-3585
    Keywords: antibodies ; immunoglobulins ; conformation prediction ; energy minimazation ; random stranting conformations ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We describe a method for predicting the conformations of loops in proteins and its application to four of the complementarity determining regions [CDRs] in the crystallographically determined structure of MCPC603. The method is based on the generation of a large number of randomly generated conformations for the backbone of the loop being studied, followed by either minimization or molecular dynamics followed by minimization starting from these random structures. The details of the algorithm for the generation of the loops are presented in the first paper in this series (Shenkin etal.[submitted]). The results of minimization and molecular dynamics applied to these loops is presented here. For the two shortest CDRs studied (H1 and L2, which are five and seven amino acids long), minimizations and dynamics simulations which ignore interactions of the loop amino acids beyond the carbon ture closely. This suggests that these loops fold independently of sequence variation. For the third CDR (L3, which is nine amino acids), those portions of the CDR near its base which are hydrogen bonded to framework are well replicated by our procedures, but the top of the loop shows singificant conformational variability. This variability persists when side chain interactions for the MCPC603 sequence are included. For a fourth CDR (H3, which is 11 amino acids long), new low-energy backbone conformations are found; however, only those which are close to the crystal are compatible with the sequence when side chain interactions are taken into account. Results from minimuzation and dynamics on single CDRs with all other CDRs removed are presented. These allow us to explore the extent to which individual CDR conformations are determined by interactions with framework only.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010408
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  • 64
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    Multiple conformations of amino acid residues in ribonuclease A (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 370-375 
    Details
    ISSN: 0887-3585
    Keywords: enzyme structure ; disorder ; refinement ; high resolution ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The highly refined 1.26 Å structure (R = 0.15) of phosphate-free bovine pancreatic ribonuclease A was modeled with 13 residues having discrete multiple conformations of side chains. These residues are widely distributed over the protein surface, but only one of them, Lys 61, is involved in crystal packing interactions. The discrete conformers have no unusual torsion angles, and their interactions with the solvent and with other atoms of the protein are similar to those residues modeled with a single conformation. For three of the residues-Val 43, Asp 83, and Arg 85-two correlated conformations are found. The observed multiple conformations on the protein surfaces will be of significance in analyzing structure-function relationships and in performing protein engineering.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010410
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  • 65
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    Structural features of ribonucleotide reductase (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 376-384 
    Details
    ISSN: 0887-3585
    Keywords: ribonucleotide reductase ; unique N-terminal domain ; nucleotide binding site ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Herpes simplex virus type 1 (HSV-1) encodes a ribonucleotide reductase which comprises two polypeptides with sizes of 136,000 (RR1) and 38,000 mol. wt. (RR2). We have determined the entire DNA sequence specifying HSV-1 RR1 and have identified two adjacent open reading frames in varicella-zoster virus (VZV) which have homology to HSV RR1 and RR2; the predicted sizes for the VZV RR1 and RR2 polypeptides are 87,000 and 35,000 mol. wt. respectively. Amino acid comparisons with RR1 and RR2 polypeptides from other organisms indicate that HSV-1 RR1 contains a unique N-terminal domain which is absent from other RR1 polypeptides apart from HSV-2 RR1. These N-terminal amino acid sequences are poorly conserved between HSV-1 and HSV-2 in contrast to the remainder of the protein which shows greater than 90% homology. Polypeptide structural predictions suggest that the HSV-1 N-terminal domain may be separated into two regions, namely, a β-sheet structure followed by a nonstructured area. Across the remainder of RR1 and RR2, comparisons also reveal blocks of amino acids conserved between the different ribonucleotide reductases, and these may be important for enzyme activity. From predictions on the structure of these conserved blocks, we have proposed that the location of a substrate binding site within RR1 is centered on three conserved glycine residues in a region which is predicted to adopt a β-sheet/turn/α-helical structure;this approximates to the structure for ADP nucleotide binding folds. Finally, we propose that the promoters for the HSV and Eptein-Barr virus (EBV) RR2 transcripts have evolved by separate evolutionary routes.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010411
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    Primary structure of a precursor to the asprartic proteinase from Rhizomucor miehei shows that the enzyme is synthesized as a zymogen (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 363-369 
    Details
    ISSN: 0887-3585
    Keywords: cDNA library ; disulphide bridges ; prosegment homology ; mRNA structure ; N-glycosylation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In order to characterize the zymogen of the milk-clotting enzyme from Rhizomucor miehei, we constructed a cDNA library on pBR327 in Escherichia coli. Aspartic proteinase-specific recombinants were isolated by colony hybridization to a specific oligonucleotide mixture, and the cDNA sequence corresponding to a precursor form of the enzyme was determined.The decuced amino sequence shows that this secreted fungal proteinase is synthesized as a precursor. The first 22 amino acid residues in this precursor constitute a typical signal peptide. The amino acid sequence of the following 47-amino-acid-long prosegment shows homology to the prosegments from both the extracellular and intracellular vertebrate aspartic proteinases, and to the prosegments from the yeast and Mucor pusillus aspartic proteinases as well. These observations suggest that all aspartic proteinases are synthesized with a prosegment and that this prosegment is essential for the correct folding of all the mature enzymes. The active Rhizomucor miehei enzyme consists of 361 amino acide residues with a total molecular weight of 38,701. Clusters of idendtities around the active site cleft support the assumption that these proteinasess have a common folding of their peptide chains. The disulphide bridges were localized in the fungal enzyme, and 2 N-glycosylation sites were identified.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340010409
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    Copolymerization of cationic monomers with acrylamide in an aqueous solution (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 29-36 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical copolymerizations of commercially available cationic monomers (M1) with acrylamide (M2) have been investigated at pH 6.1 in aqueous solutions. The cationic groups in copolymers were analyzed by a colloid titration method and the reactivity ratios were determined by the Fineman-Ross method. The values of r1 and r2 were 1.71 and 0.25 for methacryloyloxyethyltrimethylammonium chloride—M2, 1.68 and 1.26 for N,N-dimethylaminoethylmethacrylate—M2, 1.13 and 0.57 for methacrylamidopropyltrimethylammonium chloride—M2, 1.10 and 0.47 for N,N-dimethylaminopropylmethacrylate—M2, 0.47 and 0.95 for N,N-dimethylaminopropylacrylamide—M2, 0.48 and 0.64 for acryloyloxyethyltrimethylammonium chloride-M2, and 0.58 and 6.7 for dimethyldiallylammonium chloride-M2 systems. The Alfrey-Price Q and e values were calculated and the linear relationship between log Q and ultraviolet absorption maxima of cationic monomers was found.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240103
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    Functional polymers and sequential copolymers by phase-transfer catalysis. 16. Influence of sequence distribution on the mesomorphic properties of thermotropic copolyethers containing 4,4′-dihydroxybiphenyl (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 15-27 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Random and alternating thermotropic liquid-crystalline copolyethers have been synthesized from 4,4′-dihydroxybiphenyl and a 1/1 mol ratio of 1,5-dibromopentane and α,ω-dibromoalkanes by a two-phase (organic solvent-aqueous NaOH) phase-transfer-catalyzed polyetherification. Random copolyethers were prepared from α,ω-dibromoalkanes having six to twelve methylene units. Their phase behavior was compared with those of the perfectly alternating copolyethers containing five methylene units in one spacer and eight, nine, or eleven methylene units in the other, respectively. An odd-even dependence in thermal transitions has been observed in both oligomeric systems. In all cases, alternating copolyethers, even though comparatively lower in molecular weight, have given rise to higher melting and isotropization temperatures. Since the increase in the melting temperature is larger than the increase in the isotropization temperature, the thermal stability range of the mesophase has narrowed for alternating copolyethers with respect to their random copolyether counterparts.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240102
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    Chemistry of alkenyl azlactones. VII. Preparation and properties of multiazlactones derived from mercaptan-functional compounds and oligomers (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1-14 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of polymercaptans and 2-alkenyl azlactones has been further investigated, and several new multiazlactones which are liquids at room temperature have been prepared and characterized. Michael addition yielding the multiazlactones was found to take place slowly in the absence of and rapidly in the presence of acid catalysts. If basic impurities capable of forming mercaptide ion were present, however, the reaction underwent a substantially different course producing primarily ring-opened products. A source of these basic impurities was determined to be the method of preparation of the alkenyl azlactone itself. When the azlactone was prepared from its acyclic N-substituted aminoacid precursor by cyclodehydration by use of ethyl chloroformate and triethylamine, a small amount of triethylamine remained that dramatically altered the course of reaction. Nonbasic cyclodehydration agents such as dicyclohexylcarbodiimide were effective at eliminating this side reaction, as well as was the practice of adding excess acid to the reaction system to neutralize the basic impurities.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240101
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    Carbazole substituted N-acylated linear polyethylenimines (PEI). synthesis and characterization of poly[N-(9-carbazolyl)acetylethylenimine] and poly[N-(2-(9-carbazolyl))propanoylethylenimine] (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 37-60 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of carbazola substituted N-acylated polyethylenimines, namely, poly[N-(9-carbazolyl)acetylethylenimine] 20 and poly[N-(2-(9-carbazolyl))propanoylethylenimine] 21 by a grafting reaction onto PEI and isomerization polymerization of the carbazole substituted 2-oxazolines is reported. A complete acylation of amino groups in PEI by the 9-carbazolylacetyl groups was achieved by the p-nitrophenyl active ester method but PEI was only partially N-acylated by the 2-(9-carbazolyl)propanoyl groups under similar reaction conditions. The carbazole substituted 2-oxazolines, namely, 2-(9-carbazolyl)methyl-2-oxazoline 18 and (R,S)-2-[1-(9-carbazolyl)]ethyl-2-oxazoline 19, were prepared by a base induced cyclization of ß-chloroamides. The ring-opening isomerization polymerization of 18 and 19 in the molten state with a cationic initiator (dimethyl sulfate, methyl triflate, or ethylene glycol ditosylate) gave 20 and 21. Gel permeation chromatography of 20 and 21 obtained with different monomerto-initiator ratios gave evidence of a chain transfer reaction with the monomer. The polymers were characterized by elemental analyses, IR, and 1H-NMR spectroscopy.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240104
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    Syntheses of stereoregular and optically active polyamides from active 4-chloro-1-benzotriazolyl diesters and diamines (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 75-85 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new route to prepare optically active polyamides was established, based on the polycondensation of two new active diesters: the active diesters of 4-chloro-1 hydroxybenzotriazole, such as 1,1'-(terephthaloyldioxy)bis(4-chloro-benzotriazole), and 1,1'-(isophthaloyldioxy)bis(4-chlorobenzotriazole), with optically active isomers of 2,4-diaminopentane. Dipolar aprotic solvents such as N,N-dimethylformamide and dimethyl sulfoxide were used as reaction solvents. The solution polycondensation carried out in solution at room temperature afforded optically active polyamides. The aminolysis of the two active diesters was carried out as a model reaction study.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240106
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    Permeation control of ionic fluorescent probes by ambient pH changes from nylon capsule membranes depending on their microstructuresPreliminary report: T. Seki and Y. Okahata, Macromolecules, 17, 1880 (1984). Functional Capsule Membranes 20. Part 19 of this series: Y. Okahata, K. Ariga and T. Seki, J. Chem. Soc., Chem. Commun., 920 (1985). (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 61-73 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Permeations of water-soluble, ionic fluorescent probes from a large, ultrathin nylon-2,12 capsule membrane were largely affected by the ambient pH of the outer medium; permeations of cationic and anionic probes were accelerated by a factor of 50-100 in the basic and acidic medium, respectively, relative to that in the neutral-pH region. The permeation of NaCl and nonionic fluorescent probes was hardly affected by the ambient pH. The nylon capsule membrane was elucidated to have an asymmetrical structure: the dense-thin inner layer and the porous-thick outer part. The pH-sensitive permeation could be explained due to the ionization of a small amount of residual end-groups (COOH and NH2) existing in the dense-thin inner layer of the nylon capsule membrane.
    Additional Material: 6 Ill.
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    Cationic polymerization of p-methylstyrene initiated by acetyl perchlorate: An approach to living polymerization (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 87-96 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cationic polymerization of p-methylstyrene initiated by acetyl perchlorate at -78°C led to long-lived (living-like) polymers with a narrow molecular weight distribution (M̄w/M̄n = 1.1-1.4) in methylene chloride containing a common ion salt (n-Bu4NClO4) or in a less polar solvent (CH2Cl2/toluene, 1/4v/v). Under these conditions, the number-average molecular weight (M̄n) of the polymers increased in proportion to monomer conversion and was regulated by the monomer-to-initiator ratio. When fresh feeds of the monomer were repeatedly added to a completely polymerized solution, the polymerization ensued at the same rate as before and the linear increase in M̄n with monomer conversion continued. The effects of solvent polarity and the common ion salt on the polymerization showed the suppression of the ionic dissociation of the propagating species, resulting in a “nondissociated species,” to be the key factor for the formation of the long-lived polymers.
    Additional Material: 9 Ill.
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    Preparation of aromatic polyesters by direct polycondensation with thionyl chloride in pyridine (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 97-102 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mechanistic features of the reaction with thionyl chloride in pyridine were studied in a model reaction of benzoic acid with p-chlorophenol or aniline. The yields were significantly affected by the amounts of pyridine, favorably by four equivalents, and the nature of pyridine, suggesting that pyridines are not only HCl scavengers, but are also involved in the reaction itself. The reaction was assumed to proceed via a carboxylic sulfinic-anhydride intermediate different from acyl chloride, and the intermediate was found to be not so reactive that it was completely alcoholyzed by the phenol at high temperatures of more than 60°C. The reaction was successfully applied to the preparation of aromatic polyesters of high molecular weights by the direct polycondensation of aromatic dicarboxylic acids and bisphenols in pyridine at 80°C.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240108
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    Preparation of silicon-containing polymers IV. Thermally stable organosilicon poly-1,2,4-triazoles (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 103-107 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel silicon-containing poly-1,2,4-triazoles have been synthesized by the reaction of polyhydrazide precursors and aniline in polyphosphoric acid (PPA) at 260°C. The polyhydrazide intermediates were prepared from aromatic dihydrazides and silicon-containing acid dichlorides via interfacial polycondensation. These polymers and their intermediates were characterized by infrared spectroscopy (IR), solubility, and by solution viscosity. The thermal behavior of these polytriazoles has been studied by dynamic thermogravimetry.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240109
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    Determination of molecular weight distribution of nylon 12 by gel permeation chromatography (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 109-118 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular weight distribution of Nylon 12 was determined with hexafluoroisopropanol/toluene mixture as eluent by gel permeation chromatography. Calibration curve for Nylon 12 was easily obtained from that of polystyrene because the method of universal calibration was applicable among these polymers. The molecular weight distributions of Nylon 12 were always broader than expected by the theory of polymerization, i.e., most probable distribution. This result was not caused by broadening effect in gel permeation chromatography, but by polymerization itself.
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    Functional monomers and polymers. CXIX.For part CXVIII, see J, Liu, K. Kondo, and K. Takemoto, Makromol. Chem., 185, 2125 (1984). Synthesis and photochemical reaction of polymethacrylate derivative containing 6-cyanouracil (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 119-132 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A polymethacrylate derivative containing 6-cyanouracil was prepared, and its photochemical reaction was studied. The 6-cyanouracil derivative was found to show high reactivity for the photochemiccal reaction. The photochemical-reaction product was identified as a cyclobutanetype photodimer, and the photodimer was formed in high yield even from the monomeric compound of 6-cyanouracil under UV irradiation in low concentration. The quantum yield of the photodimerization of the 6-cyanouracil derivative was greater than that of the thymine derivative. The photodimerization of the 6-cyanouracil derivative could not be quenched by usual triplet quenchers, but was found to be quenched by the polymeric derivative of adenine, suggesting a specific interaction.
    Additional Material: 4 Ill.
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    Synthesis of poly dithioesters and cyclization to 1, 3-dithiolium (dithiafulvenium) salts (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 147-153 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Piperidinium dithiobenzoate and piperidinium tetrathioterephthalate react with α-halo carbonyl compounds to give small molecules and polymers which, upon dehydrative cyclization with H2SO4, yield materials containing the 1,3-dithiolium ring. Maximum yields are obtained by use of phase-transfer techniques and the solvent system H2O/CH2Cl2. The cyclized polymers are soluble in sulfuric acid, and films can be made from (CF3)2 CHOH solutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240113
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    Polymers of ortho-vinylbenzaldehyde (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 133-145 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ortho-vinylbenzaldehyde has been prepared in a three-step synthesis. Vacuum-degassed monomer was polymerized with azodiisobutyronitrile initiator in bulk and in solution in 2-butanone. The kp/kt1/2 value at 60°C is 4.7 × 10-2 L1/2 mol-1/2s-1/2. This is about twice the ratio for styrene. Chain transfer to monomer appears to be significant. Insoluble, crosslinked products were produced at high conversions, because of chain transfer to polymer. Tg of poly(ortho-vinylbenzaldehyde) was found to be 142°C.Polymers made under N2 atmosphere often contained acetal groups. These can be produced by acid catalysis in the presence of small concentrations of ortho-vinylbenzyl alcohol. A laddertype structure is produced.The monomer is capable of photoinitiation. Insoluble gels were produced in bulk monomer at all conversions. The initiation rate was very high and crosslinking resulted from combination of radicals produced from photolysis of the pendant 0-benzaldehyde groups in the macromolecules.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240112
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  • 80
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    Novel optical resolution of an unprotected adenine derivative followed by grafting the pendant onto polyethylenimine (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 167-171 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240115
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  • 81
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    Cationic polymerization initiated by intercalation compounds of lewis acids. II. Initiating ability and mechanism of action of the initiatorsFor the first article of the series see Ref. 7. (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 155-165 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The initiating ability of the graphite intercalation compounds (GICs) of SbCl5, FeCl3, and AlBr3 was investigated. It was found that GICs were able to initiate the polymerization of monomers of different types-cyclosiloxanes, 1,2-epoxides, vinyl ethers, lactones, and vinyl monomers. GICs of SbCl5 initiated also the polymerization of tetrahydrofuran. The interaction of the monomers (with the exception of the lactones) caused a size increase of the GICs and deformations in their lamellar structure. Relatively high-molecular poly(vinyl ethers) and polydimethylcyclosiloxanes were obtained. The mechanism of action of GICs was discussed.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240114
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  • 82
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    Boron-nitrogen polymers. I. Mechanistic studies of borazine pyrolyses (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 173-185 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyrolyses of B-triamino-N-triphenyl-, B-triamino-N-trimethyl-, and B-trianilino-borazines were performed between 150 and 300°C. Initial stages of degradation were accompanied by liberation of ammonia in addition to the expected aniline or methylamine; this was most pronounced for the methyl borazine. Aniline elimination proceeded more readily with the B-anilino than the B-amino isomer. Data obtained support a ring opening mechanism resulting in telomerizaton accompanied by aniline liberation and formation first of singly then doubly bridged dimers and finally doubly bridged tetramers. Thermal exposure up to 1000°C failed to give pure boron nitride; carbon was invariably retained.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240116
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  • 83
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    Preparation of polyamides and polyesteramides by the direct polycondensation with tosyl chloride and N-methylimidazole (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 187-189 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240117
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  • 84
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    Radical grafting from carbon black by carbon black having hydroxy methyl group/ceric ion redox system (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 191-194 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240118
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  • 85
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    Radical copolymerization of γ-methylene-Δα,β-butenolide derivative: ethyl(E)-5-OXO-2,5-dihydrofuran-2-ylidene-acetate (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 197-202 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical polymerications including co- and terpolymerizations of a γ-methylene-Δα,β-butenolide derivative, ethyl (E)-5-oxo-2,5-dihydrofuran-2-ylideneacetate(EODY) was investigated. The monomer had no homopolymerizability but copolymerized with styrene (ST) and 1,3-cyclohexadiene to yield alternating copolymers. From IR and 1H-NMR spectra of the copolymers, the 1,4-addition was confirmed to exclusively occur for the conjugated double bond of EODY. Terpolymerization for the system involving an acceptor monomer such as maleic anhydride, α-chloromaleic anhydride, or 7,7,8,8-tetracyanoquinodimethane in addition to ST and EODY gave the terpolymer containing about 50 mol% of ST, in spite of a high fraction of ST in the feed. It was inferred that such an apparent behavior of EODY as an acceptor monomer could be due to a resonance-stabilization of the propagating radical having EODY as a terminal unit, which is also responsible for the poor yields of the copolymers and terpolymers.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240201
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  • 86
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    Synthesis and characteristics of microspheres of polystyrene derivatives (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 203-213 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two sytrene derivatives formylstyrene and styrene sulfonylcholoride, were synthesized. Polymeric microspheres in diameters ranging from 0.1 to 2 μm were synthesized by polymerization of chlormoethylstyrene, formylstyrene, and styrene sulfonylcholoride in organic solvents, in the presence of appropriate surfactants. The kinetics of microsphere formation were studied. The molecular weight distribution of the products was determined by gel permeation chromatography. Conditions for binding various amino ligands to the microspheres were also established.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240202
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  • 87
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    Photolabeling studies of polymer-cell surface interaction. Evaluation of 3-[(4-azidophenyl)dithio]propionic acid as a polymer-bound photolabel (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 241-253 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-[(4-Azidophenyl)dithio]propionic acid (1a) was prepared in four steps from 4,4′-diamino-diphenyldisulfide. Attachment of 1a to poly[(3-hydroxypropyl)oxirane] was accomplished under very mild conditions via an acid-catalyzed caarbodiimide coupling. Photolysis of polymer-bound 1a with an electronic flash unit proceeded without detectable disulfide bond cleavage. Mild reduction of the disulfide bond of an analogue of 1a which carried no azido group confirmed that 1a should be useful in photolabeling studies of polymer-cell surface interaction.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240204
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  • 88
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    Synthesis of polyamide containing optically active thymine derivative as a grafted pendant (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 269-278 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new route to polyamides containing optically active thymine groups as pendants has been established. The method is based on the grafting of (-) and (±)-2-(thymin-1-yl)propionic acid [(-) and (±) TPA] onto a polyamide containing hydroxyl groups. The hydroxy polyamide was prepared by selective N-acylation of an active diester of N-hydroxy-5-norborene-2,3-dicarboxamide (HONB), N,N'-(isophthaloyl-dioxy)-bis(5-norbornene-2,3-dicarboximide) (IPBONB), with 1,3-diamino-2-hydroxypropane (AHP). Model compounds (-) and (±)-(1,3-dibenzoylamino-2-propyl)2-(thymin-1-yl)propionate[(-) and (±) (BAPTP)] were prepared by direct, low-temperature esterification before synthesizing the polymer.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240206
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  • 89
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    Polymerization of para-xylylene derivatives (parylene polymerization). III. Heat effects during deposition of parylene N at different temperatures (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 215-240 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermal effects accompanying the vacuum deposition of poly-para-xylene (Parylene N) at different temperatures have been studied by following the changes in the temperature of the substrate. Similarly to the case of polychloro-para-xylylene (Parylene C), two distinct exothermic effects were observed; one discrete, resulting in sharp exothermic spikes and the other continuous, resulting in the shift of the baseline. The spike effect, attributed to the solid-state polymerization of para-xylylene, is observed at the low-temperature range, the upper limit of which moves higher for higher deposition rates. The shift of a baseline as a function of deposition temperature exhibits two maxima, one independent of deposition rate and the second moving toward higher temperatures (that is, toward the first maximum) for higher deposition rates. First maximum falls at about —72°C and is attributed to the melting point of para-xylylene crystals. X-ray diffraction studies of polymer samples have shown that the existence of the second maximum is always followed by the appearance of an additional crystalline phase in the respective range of deposition temperatures. When the deposition rate is high enough, the second maximum merges with the first one, or virtually disappears. Under such conditions the new crystalline phase is no more detectable. It is postulated that the evolution of the additional amount of heat resulting in the appearance of the second maximum is due to the cyclization reaction and the formation of cyclic oligomers. This reaction very likely requires a particular spatial arrangement of monomer molecules and, therefore, it is suggested to take place in certain domains of the crystalline lattice.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240203
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  • 90
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    Polynuclear and halogenated structures in polyphenylenes synthesized from benzene, biphenyl, and p-terphenyl under various conditions: Characterization by laser desorption/fourier transform mass spectrometry (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 255-267 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyphenylenes made by reaction of benzene, biphenyl, or p-terphenyl with metal halide catalyst-oxidant systems are complex mixtures of dissimilar oligomers, which include halogenated and polynuclear structures, according to positive and negative-ion laser desorption/Fourier transform mass-spectral analyses. Polymerization of benzene with metal-chloride salts that terminate chain elongation by chlorination of the end rings appears to decrease formation of polynuclear structures by providing a competing pathway for chain termination. Polynuclear structures occur to a greater extent with oligomerization of biphenyl than with benzene, presumably because of isomerization and increased opportunity for π overlap during propagation. Electrical conductivities of polyphenylenes made by various routes should not be discussed solely in terms of the linear poly(p-phenylene) structure.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240205
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  • 91
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    An ESCA and plasma emission study of the plasma polymerization of 1-fluoronaphthalene and octafluoronaphthalene (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 279-286 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240207
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  • 92
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    Correlation of thermal degradation mechanisms: Polyacetylene and vinyl and vinylidene polymers (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 301-316 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal degradation of poly(vinyl bromide) (PVB), poly(vinyl chloride) (PVC), poly(vinyl alcohol) (PVA), poly(vinyl acetate) (PVAc), poly(vinyl fluoride) (PVF), poly(vinylidene chloride) (PVC2), and poly(vinylidene fluoride) (PVF2) has been studied by direct pyrolysis-mass spectrometry (DP-MS) and flash pyrolysis-gas chromatography-mass spectrometry techniques. Vinyl and vinylidene polymers exhibit two competitive thermal degradation processes: (1) HX elimination with formation of polyene sequences which undergo further moleculaar rearrangements, and (2) main-chain cleavage with formation of halogenated or oxigenated compounds. The overall thermal degradation process depends on the prevailing decomposition reaction in each polymer; therefore, different behaviors are observed. The thermal degradation of polyacetylene (PA) has also been studied and found important for the elucidation of the thermal decomposition mechanism of the title polymers.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240209
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  • 93
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    Preparation and structural characterization of poly(4-vinylphenylacetate-co-maleic anhydride) (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1487-1495 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(4-vinylphenylacetate-co-maleic anhydride) was synthesized by free-radical initiation to yield a 1:1 copolymer over a 0.2-0.8 mole fraction range of monomer feed in maleic anhydride. Evidence of 1:1 charge transfer complex between 4-vinylphenylacetate and maleic anhydride was obtained in the UV region at 355 nm. The 13C NMR chemical shifts and 1H NMR integration data indicate that poly(4-vinylphenylacetate-co-maleic anhydride) has an alternating and stereoregular structure. The molecular weight of poly(4-vinylphenylacetate-co-maleic anhydride) was controlled by using specific solvents and initiator concentrations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240706
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  • 94
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    Monomer-isomerization polymerization. XXI.Part XX of this series is ref. 14.. Monomer-isomerization copolymerization of 3-methyl-1-butene and 2-pentene with ziegler-natta catalyst (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1505-1510 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-Methyl-1-butene (3M1B) was found to undergo monomer-isomerization copolymerization with 2-pentene (2P) in the presence of Ziegler-Natta catalyst to give a copolymer exclusively consisting of 3M1B and 1-pentene (1P) units, the same as that obtained from copolymerization of 3M1B and 1P. The apparent copolymerization parameters were determined. The amount of 3M1B unit incorporated in the copolymers was found to increase in the copolymerization system of 3M1B-2P more than in that of 3M1B-1P. The polymers consisting of nearly complete 3M1B units were produced at a rapid rate through monomer-isomerization copolymerization of 3M1B with 2P in the presence of TiCl3 - (C2H5)3Al catalyst.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240708
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  • 95
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    Preparation of conducting copolymers by oxidative electropolymerization of 2,2′-bithiophene with pyrrole (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1529-1537 
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    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various feed ratios of 2,2′-bithiophene (BT) and pyrrole (PY) were electropolymerized to low conversion and the polymers analyzed for their mer ratios. The polymeric product was rich in polypyrrole (PPY), but the composition could be varied by control of the electrode potential. The increase in BT content is not linear with composition, and the physical evidence indicates oxidative copolymerization and not the formation of the two homopolymers. The data can be interpreted on a copolymerization equation despite the absence of steady state conditions. Sets of reactivity ratios were determined for the polymers formed at two potentials. The electrical efficiencies for polymer formation approach stoichiometric values for oxidative polymerization.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240711
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  • 96
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    Synthesis of N-substituted phenoxazine polymers bearing vinyl backbone (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1565-1575 
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    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinyl monomers bearing N-substituted phenoxazine or 2,8-dimethylphenoxazine units were synthesized starting with the corresponding phenoxazines. N-substituents were 2-vinylbenzyl-oxycarbonylethyl group prepared via 2-carboxyethyl group, 3-methacrylamido-, 3-acrylamido-, or 3-(4-styrenesulfonamido)-propyl group prepared via 3-aminopropyl group, vinylbenzyl, or 2-vinyloxyethyl group attached by the displacements of sodium salts of the phenoxazines to the chlorides, and 2-methacryloyl- or 2-acryloyl-oxyethyl group prepared via 2-hydroxyethyl group. Free-radical polymerixations of these novel monomers proceeded smoothly, except those with 2-vinyloxyethyl group, which were susceptible to BF3-etherate. Changes of the visible absorption spectrum of iodine in THF with addition of the monomers and polymers were considerable, with the appearance of new absorption peaks or shoulders in major cases.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240714
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  • 97
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    Selective separation of water-ethanol mixture through synthetic polymer membranes having carboxylic acid as a functional group (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1585-1597 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Separation of water-ethanol mixture through a membrane was carried out by pervaporation using a membrane which provided a hydrogen-bonding interaction. A membrane obtained from poly(acrylic acid-co-acrylonitrile) was effective for a selective separation of water from aqueous ethanol solution by pervaporation technique. Spectroscopic and flux analyses verified that this high selectivity toward water was attributed to the hydrogen-bonding interaction between water and acrylic acid (carboxylic acid) unit in the membrane. On the other hand, a membrane from poly(acrylic acid-co-styrene) preferentially permeated ethanol in the low water feed concentration region.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240716
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  • 98
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    Thermal properties of nylons containing carbonyl groups (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1657-1674 
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    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nylons containing carbonyl groups in backbone chains were prepared and their response to heat was studied. The carbonyl groups were introduced using either HOOC(CH2)4CO(CH2)4COOH or H2N(CH2)5CO(CH2)5NH2 in the initial monomer compositions. In addition to pyrolysis of these polyamides, the progress of chemical and physical changes as a function of temperature was continuously monitored and analyzed by FT-IR spectroscopy on cast films placed in an environmental chamber. Introduction of the carbonyl groups into the polymer backbone resulted in a significant reduction of the thermal stability of the corresponding polyamide. Possible mechanisms for the thermal degradation entailing these carbonyl groups and N-acylamide compounds are discussed.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240723
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  • 99
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    Synthesis and properties of semiconducting aromatic polyquinonediimines (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1703-1716 
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    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new class of poly-conjugated polymers has been obtained by condensation of anthraquinones with aromatic diamines in polyphosphoric acid. The polymers are black, intractable powders. Toward obtaining tractable materials, the effect of monomer structure on polymer tractability has been studied. Copolymerizations were also carried out to “soften” these materials. Electrical conductivities in the semiconducting range, 10-4- 10-8 (ohm cm)-1 were observed. Doping with iodine showed small increases.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/pola.1986.080240727
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  • 100
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    Evolution of H2O and CO2 during the copper-catalyzed oxidation of isotactic polypropylene (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 389-403 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics and mechanism of H2O and CO2 evolution during uncatalyzed and copper(oxide)-catalyzed (Cu, CuO, CuO0.67) oxidation of isotactic polypropylene have been investigated in detail for various catalysts over a range of temperatures (90-150°C). These volatiles were determined chromatographically; H2O and CO2 represent the main volatiles of the oxidation, comprising about 80 mol % of all volatiles. Uncatalyzed oxidation evolves ca. 1 mol of H2O and 1 mol of CO2 for each unit mole of polymer oxidized, while catalyzed oxidation produces 2 mol of H2O and ca. 1.2 mol of CO2 for each unit mole of polymer. These results indicate that secondary as well as tertiary H atoms on the polymer chains are involved in hydroperoxide formation and decay. The oxidation mechanism has been formulated and evaluated on this basis. It consists essentially of two parallel oxidation reactions involving tertiary and secondary groups (H atoms and hydroperoxides), respectively. The mechanism can be represented by first- and pseudo-first-order reactions in series: (1) oxygen absorption showing induction periods; (2) hydroperoxide formation and decay (plateaus are reached); (3) H2O evolution from the decay of hydroperoxides; and (4) subsequent CO2 production involving chain scission. Arrhenius parameters for all oxidation reactions (uncatalyzed and catalyzed) are also presented. It appears that CuO0.67 is the most efficient catalyst of those investigated.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240301
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