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  • 1985-1989  (9,915)
  • 1905-1909
  • 1987  (9,915)
  • Chemistry  (8,271)
  • Life and Medical Sciences  (1,644)
Material
Years
  • 1985-1989  (9,915)
  • 1905-1909
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pharmacy world & science 9 (1987), S. 305-314 
    ISSN: 1573-739X
    Keywords: Atrial natriuretic factor ; Blood pressure ; Chemistry ; Diuresis ; Homeostasis ; Kidney ; Muscle, smooth ; Natriuresis ; Receptors, endogenous compounds ; Renin-angiotensin system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract It is now known that cardiac atria play an important role in blood pressure and volume regulation. Mechanical distension of the atria results in the release of a potent diuretic and natriuretic agent or agents termed the atrial natriuretic factor (ANF). Several structurally related forms of ANF exist in man and it is thought that these represent precursory forms of a single optimally active molecule and/or the presence of more than one form of active ANF. The chemical structure of ANF between different mammalian species is similar. ANF receptors have been identified in kidney, brain, vascular endothelial and smooth muscle cells, tracheal and bronchial smooth muscle and the adrenal glands of many mammalian species, including man. This would suggest that ANF influences blood pressure and volume homoeostasis by affecting any one of a number of biochemical or physiological mechanisms via different target tissues. ANF is now considered a potentially valuable therapeutic agent for the treatment of hypertension and congestive heart failure. Synthesis of potent receptor antagonists could be extremely useful in the treatment of various clinical situations which are produced or complicated by endogenously produced ANF, such as chronic orthostatic hypotension.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987) 
    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
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  • 3
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We present a high-resolution electron microscopic study of the sidearms on microtubules and vesicles that are suggested to form the crossbridges which produce the microtubule-based vesicle transport in squid axoplasm. The sidearms were found attached to the surfaces of the anterogradely transported vesicles in the presence of ATP. These sidearms were made of one to three filaments of uniform diameter. Each filament measured 5-6 nm in width and 30-35 nm in length. The filaments in some of the sidearms had splayed apart by pivoting at their base, thereby assuming a “V” shape. The spread configuration illustrated the independence of the individual filaments. The filaments in other sidearms were closely spaced and oriented parallel to each other, a pattern called the compact configuration. In axoplasmic buffer containing AMP-PNP, structures indistinguishable from the filaments of the sidearms on the vesicles were observed attached to microtubules. Pairs of filaments, thought to represent the basic functional unit, were observed attached to adjacent protofilaments of the microtubules by their distal tips. These data support a model of vesicle movement in which a pair of filaments within a sidearm forms two crossbridges and moves a vesicle by “walking” along the protofilaments of the microtubule.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 31-38 
    ISSN: 0886-1544
    Keywords: microtubule assembly ; proleolysis ; Vinca drugs ; Zn2+-induced assembly ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Limited proteolysis of tubulin with subtilisin results in cleavage of both the α and β subunits, releasing small peptides from the C-terminal ends. At 37°C the digested tubulin assembles into polymorphic structures: microtubules with attached ribbons in the presence of GTP, rings in the presence of GDP, and protofilament spirals in the presence of vinblastine. Undigested tubulin does not assemble under these conditions. Rings and Vinca-induced spiral structures are assembled from undigested tubulin only when microtubule-associated proteins, high Mg2+ concentrations, or polycations are present. Thus, cleavage with subtilisin affects assembly in a manner similar to the addition of these agents. It appears that binding of positively charged substances may act by neutralizing the charge on the highly acidic C-terminal regions of the α- and β-subunits, while cleavage with subtilisin produces the same effect by removing these peptides. Undigested and subtilisin-digested tubulin form sheets of protofilaments in the presence of Zn2+, which indicates that the binding sites for the 2-3 Zn2+ ions necessary to induce sheet formation do not reside in the C-terminal regions of the monomers.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 46-53 
    ISSN: 0886-1544
    Keywords: actin filament ; fertilization ; fluorescent labeled phallotoxins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of actin filaments in the cortical layer of sea urchin eggs during fertilization has been investigated by light microscopy using fluorescently labeled phallotoxins. The cortical layer of both whole eggs and cortices isolated on a glass surface was examined. In cortices of unfertilized eggs, numerous fluorescent spots were seen, which may correspond to short actin filament cores in microvilli. After insemination, one of the sperm-attaching points on the egg surface first became strongly fluorescent. This fluorescence grew around the point of sperm penetration with the growth of the fertilization cone. Then, the cortical layer of the egg around the fertilization cone became strongly fluorescent and the fluorescence propagated in a wavelike manner over the entire cortex. The mechanism of the propagation of actin polymerization is discussed.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 87-93 
    ISSN: 0886-1544
    Keywords: movement ; flagellar ; beat, flagellar ; stigma ; high-speed microcinematography ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Chlamydomonas cells sucked onto micropipettes were filmed at 500 frames/sec and analyzed as to their forward beating mode. A comparison with freely swimming cells revealed that the flagella of the sucked cells beat in a normal threedimensional manner, with beat frequencies that correspond to those of freely swimming cells. Most beats were synchronous. but not symmetrical; cis- and trans-flagellum appear to beat in a slightly different manner. Some cells beat synchronously throughout, but mostly synchrony was interrupted by a single asynchrony or up to incessant asynchronies, caused by transient accelerations of the trans- (fo-) flagellum. Only rarely did cis- and trans-flagella have different but constant beat frequencies. Helical swimming of Chlamydomonas more likely is due to the beat asymmetries of the two flagella than to differences of beat frequencies. In our records, the stigma is on the inside of the helical swimming path.
    Additional Material: 9 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 110-115 
    ISSN: 0886-1544
    Keywords: microtubules ; antitubulin ; particle translocalion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microtubules have been demonstrated to be a substrate for organelle transport and particle translocation in vitro and in vivo. Subsequent to a previous report of inhibition of axonal transport of exogenous tracers in vivo using antiserum NS-20 against tubulin (Johnston et al: Brain Res. 1986), we now show disruption of particle movement in extruded squid axoplnsm using this unique immunological probe. Using video-enhanced contract-differential interference contrast (AVEC-DIC) microscopy, we examined the properties of particle movement along microtubules and demonstrated that bolh the velocity of particle movement and the numbers of particles moving are decreased in the presence of NS-20 antiserum or NS-20 affinity-purified antibodies but. not in the presence of another antiserum against tubulin. The amount of microtubule substrate does not change in the presence of any of the antisera. In conclusion, we suggest that NS-20 antibodies bind near or at a site on the tubulin molecule which is critical in the mechanism of particle transport, and provide a direct immunological probe to examine the mechanism of microtubule involvement in axonal transport.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 116-128 
    ISSN: 0886-1544
    Keywords: actin filament bundle ; macrociliary cell ; Clenophores ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Macrocilia are thick compound ciliary organlles arising individually from elongated epithelial cells on the lips of beroid ctenophores. A giant wedge-shaped bundle of microfilaments extends 25-30 μm from the base of each macrocilium to the lower end of the cell, terminating at a junction with an underlying smooth muscle cell. The broad end of the microfilament bundle is anchored to the macrocilium by striated rootlet fibers that extend from the basal bodies into the bundle and are linked to the microfilaments by periodic bridges. Fluorescence microscopy of rhodamine-phalloidin stained intact tissue, dissociated macrociliary cells, and Triton/glycerol-isolated bundles shows that the microfilaments contain actin. The microfilaments run generally parallel to the long axis of the bundle but are not highly ordered. Filaments decorated with myosin S1 show a uniform polarity with arrowheads pointing away from the tapered membrane-associated end of the bundle. No variations in bundle length (nor changes in rootlet periodicity) were observed in tissue fixed under conditions of calcium activation. Isolated bundles did not contract in Mg-ATP, even though detached macrocilia underwent reactivated beating and sliding disintegration. Macrocilia arc used to bite through food organisms or transport prey into the stomach. The actin filament bundles probably play a supporting role as a structural linker between macrocilia and subepithelial muscle fibers and may serve as intracellular tendons lo mechanically coordinate the motor activities of macrocilia and muscles during prey ingestion.
    Additional Material: 8 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 129-137 
    ISSN: 0886-1544
    Keywords: actin mRNA ; sclerotium ; polysomes ; Triton X-100 extraction ; cycloheximide ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Translationally active plasmodia of the syncytial slime mold Physarum polycephalum develop into translationally dormant sclerotia during starvation. Although functional mRNA and ribosomes exist in sclerotia, protein synthesis is suppressed at the level of initiation. To test the possibility that alterations in the cytoskeleton may limit protein synthesis, we have examined the distribution of polysomes and actin mRNA in the cytoskeletal (CSK) and soluble (SOL) fractions of Triton X-100-extracted plasmodia and sclerotia. Most of the polysomes and actin mRNA were located in the CSK of plasmodia, while most of the ribosomes and actin mRNA were located in the SOL of sclerotia. The results suggest that ribosomes and mRNA shift from the CSK to the SOL as protein synthesis is suppressed during starvation. Plasmodia and sclerotia can be induced to accumulate excess polysomes by treatment with low levels of the elongation inhibitor cycloheximide. Treatment of plasmodia with cycloheximide caused excess polysomes to accumulate in the SOL, suggesting that the CSK contains a limited capacity for binding translational components and that the association of polysomes with the cytoskeleton is not required for protein synthesis. Treatment of sclerotia with cycloheximide, however, caused polysomes and actin mRNA to accumulate in the CSK, suggesting that the selcrotial cytoskeleton, although depleted in ribosomes and mRNA, is capable of binding translational components. It is concluded that alterations in the sclerotial cytoskeleton are not involved in translational control.
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  • 10
    ISSN: 0886-1544
    Keywords: calcium ; protein phosphorylation ; TFP ; Triton-extracted model ; ciliary orientation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To explore possible roles of calmodulin in Ca2+-induced ciliary reversal, we tested the effects of calmodulin antagonists on Triton-extracted models of Paramecium. In the extracted models prepared by the method of Naitoh and Kaneko [Science 176:523-524, 1972], the Ca2+ -induced ciliary reversal was not inhibited by calmodulin antagonists, trifluoperazine (TFP), or 5-chloro-l-naphthalenesulphone amide (W-7). However, in the presence of adenosine 3′,5′-cyclic mono-phosphate (cAMP), whose concentration is below the one that alters the ciliary direction, TFP inhibited ciliary reversal and the models swam forward at 10-5 M Ca2+. When the washing medium in the preparation of the extracted models was replaced with one containing MgCl2, the extracted model showed sensitivity to calmodulin antagonists without addition of cAMP; at 10-5 M Ca2+, 40 μM TFP or 100 μM W-7 inhibited the ciliary reversal and the models swam forward. Such effect of antagonists was abolished by an inhibitor of cAMP-dependent protein kinase. On the other hand, addition of cAMP enhanced the inhibitory effect of antagonists. These results suggest that calmodulin antagonists act to increase the extent of cAMP-dependent protein phosphorylation that inhibits the Ca2+ -induced ciliary reversal.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987) 
    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
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 178-186 
    ISSN: 0886-1544
    Keywords: colchicine binding ; tubulin ; immunofluorescence ; PtK2 ; Pk15 ; SV-3T3 cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: 2-methoxy-5-(2,3,4-trimethoxyphenyl) 2,4,6-cycloheptatrien-1-one (MTC) is a synthetic colchicine analogue, lacking the B ring of the alkaloid (Fitzgerald: Biochem. Pharmacol. 25:1381-1387, 1976). MTC has been shown to bind reversibly to the colchicine binding site of tubulin and to inhibit microtubule assembly in vitro (Andreu et al: Biochemistry 23:1742-1752, 1984; Bane et al: J. Biol. Chem. 259:7391-7398, 1984). Its action on different cultured cell lines (PtK2, Pk15, and SV-3T3) has now been studied. 0.2 × 10-6 M MTC stopped Pkl5 and SV-3T3 cell growth, inducing an accumulation of mitoses in a few hours. Removal of MTC from the culture medium rapidly restored normal mitotic index and growth rates. Partial depolymerization of the cytoplasmic microtubules of PtK2 cells was observed at concentrations ranging from 2 to 5 × 10-7 M. Maximal microtubule network depolymerization was obtained after 4 h of treatment with 2 to 5 × 10-6 M MTC or at a higher MTC concentration (2 × 10-5 M) for less than 2 h. Removal of 2 × 10-5 M MTC (the highest MTC concentration used) from the culture medium resulted in almost complete microtubule polymerization after 10 min of drug recovery and a normal microtubule network in 20-30 min.MTC constitutes an antimitotic drug directed to the colchicine site. It is water-soluble, shows a fast and reversible action, and may therefore be employed as a convenient tool to study cellular microtubule-dependent functions.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 238-249 
    ISSN: 0886-1544
    Keywords: human lymphoblastoma cells ; microtubule organizing centers ; isolation centrioles ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A procedure adapted from that described by Mitchison and Kirschner [Nature 312:232-237, 1984] was used to isolate centrosomes from human lymphoid cells. High yields of homogeneous centrosomes (60% of the theoretical total, assuming one centrosome per cell) were obtained. Centrosomes were isolated as pairs of centrioles, plus their associated pericentriolar material. Ultrastructural investigation revealed: 1) a link between both centrioles in a centrosome formed by the gathering in of a unique bundle of thin filaments surrounding each centriole; 2) a stereotypic organization of the pericentriolar material, including a rim of constant width at the proximal end of each centriole and a disc of nine satellite arms organized according to a ninefold symmetry at the distal end and; 3) an axial hub in the lumen of each centriole at the distal end surrounded by some ill-defined material.The total protein content was 2 to 3 × 10-2 pg per isolated centrosome, a figure that suggests that the preparations were close to homogeneity. The protein composition was complex but specific, showing proteins ranging from 180 to 300 kD, one prominent band at 130 kD, and a group of proteins between 50 and 65 kD. Actin was also present in centrosome preparations.Functional studies demonstrated that the isolated centrosomes were competent to nucleate microtubules in vitro from purified tubulin in conditions in which spontaneous assembly could not occur. They were also very effective at inducing cleavage when microinjected into unfertilized Xenopus eggs.
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 274-283 
    ISSN: 0886-1544
    Keywords: focal contacts ; vimentin filaments ; microtubules ; immunofluorescence ; platinum replicas ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Double immunofluorescence staining of quail embryo fibroblasts with rabbit antibody to vinculin and mouse monoclonal antibody to vimentin revealed a coincidence between fluorescence patterns for cell-substrate focal contacts and intermediate filaments. Most of the vinculin-containing adhesion plaques coincided with the ends of vimentin-positive fibrils.This association was further corroborated by immunoelection microscopic observations of the cytoskeletons of quail and mouse fibroblasts using a platinum replica technique. The intermediate filaments were identified either by direct treatment with antivimentin IgM or by an indirect immunogold staining method.Colcemid treatment of the cells caused a collapse of intermediate filaments and destroyed their association with focal contacts. During the early stages of the colcemid-induced collapse of the intermediate filaments, single vimentin fibrils appeared to retain their association with focal contacts.The possible role of the intermediate filaments in the formation and maintenance of focal contacts is discussed.
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 284-291 
    ISSN: 0886-1544
    Keywords: tyrosination ; acetylation ; post-translational modifications ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have examined the distribution of acetylated α-tubulin using immunofluorescence microscopy in fibroblastic cells of rat brain meaninges. Meningeal fibroblasts showed heterogenous staining patterns with a monoclonal antibody against acetylated α-tubulin ranging from staining of primary cilia or microtubule-organising centers (MTOCs) alone to extensive microtubule networks. Staining with a broad spectrum anti-α-tubulin monoclonal indicated that all cells possessed cytoplasmic microtubule networks. From double-labeling experiments using an antibody against acetylated α-tubulin (6-11B-1) and antibodies against either tyrosinated or detyrosinated α-tubulin, it was found that acetylated α-tubulin and tyrosinated α-tubulin were often segregated to different microtubules. The microtubules containing acetylated but not tyrosinated α-tubulin were cold stable. Therefore, it appeared that in general meningeal cells possessed two subset of microtubules: One subset contained detyrosinated and acetylated α-tubulin and was cold stable, and the other contained tyrosinated α-tubulin and was cold labile. These results are consistent with the idea that acetylation and detyrosination of α-tubulin are involved in the specification of stable microtubules.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 302-311 
    ISSN: 0886-1544
    Keywords: flagella ; cAMP ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When demembranted axonemes of Chlamydomonas were reactivated with Mg ATP, the proportion of motile axonemes was significantly increased by the preence of either phosphodiesterase (PDE) or protein inhibitor of cAMP-dependent kinase (PKI). The effect of PDE was cancelled by the addition of cAMP. These findings strongly suggest that the axoneme samples have endogenous cAMP, which can reduce the proportion of motile axonemes via phosphorylation. This inhibitory effect of cAMP on Chlamydomonas axonemes is opposite to its stimulatory effect on the axonemal motility in other organisms so far reported. PKI or PDE activated the motility motility either in the absence of Ca2+, when the axonemes beat with an asymmetric waveform, or in 10-5M Ca2+, when the axonemes beat with a symmetric waveform. This cAMP-dependent regulation of motility was observed with the axonemes from which detergent-soluble material had been removed, indicating that the proteins responsible for the regulation still remained in the axonemes. Preliminary in vitro phosphorylation stdies have implicated two polypetides as candidates for the target protein of cAMP-dependent protein kinase: one with a molecular weight of 270 kD and the other with a much larger molecular weight.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 345-359 
    ISSN: 0886-1544
    Keywords: alpha-actinin ; cytoskeleton ; muscle cells ; nonmuscle cells ; stress fiber ; myofibril ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study report the first development of a fluorescently labeled filamin. Smooth muscle was labeled with fluorscent dyes in order to study its interaction with stress fibers and myofibrils, both in living cells and in permeabilized cells. The labeled filamin bounds to the Z bands of isolated cross-striated myofibrils and to the Z bands and intercalated discs in both permeabilized embryonic cardiac myocytes and in frozen sections of adult rat venticle. In permeabilized embryonic chick myotubes, filamin bound to early myotubes but was absent at later stages. In living embryonic chick myotubes, the fluorescently labeled filamin was incorporated into the Z bands of myofibirls during early and late stages of develoment but was absent during an intermediate stages. In living cardiac myocytes, filamin-IAR was incorporated into nascent as well as fully formed sarcomeres throughout develoment. In permeabilized nonmuslce cells, labeled filamin bound to attachment plaques and foci of polygonal networks and to the dense bodies in stress fibers. The periodic bands of filamin in stress fibers had a longer spacing in fibroblasts than in epithelial cells. When injected into living cells, filamin was readily incorporated into stress fibers in a striated pattern. The fluorescent filamin bands were broader in injected cells, however, than they were in permeabilized cells. We have interpreted these results from living and permeabilized cells to mean that native filamin is distributed along the full lengh of the actin filaments in the stress fibers, with a higher concentration present in the dense bodies. A sarcomeric model is presented indicating the position of filamin with respect to other proteins in the stress fibers.
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  • 18
    ISSN: 0886-1544
    Keywords: chemotaxis ; cell motility ; cellular polarity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Amebae of Dictyostelium discoideum normally chemotax to aggregation centers by assessing the direction of outwardly moving, nondissipating waves of the chemoattractant cAMP. However, D. discoideum amebae can also assess the direction of a relatively stable spatial gradient. We demonstrate that amebae migrating towards the “source” of a stable, spatial gradient move faster, extend fewer pseudopodia, and turn less frequently than amebae migrating away from the “source” in the same spatial gradient. In addition, amebae extend lateral pseudopods in a polarized fashion from the anterior half of the cell, and do so as frequently towards the source as away from the source. However, those formed towards the source more often produce a turn than those formed away from the source. These results suggest that there may be two decision-making systems, one localized in the pseudopods, and one along the entire cell body; they support the suggestion that Dictyostelium amebae may employ a temporal mechanism to assess the direction of a spatial gradient of chemoattractant.
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  • 19
    ISSN: 0886-1544
    Keywords: nuclear migration ; microtubules ; F-actin ; root hairs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A prominent feature of tip growth in filamentous plant cells is that the nucleus often migrates in step with the tip as it extends. We have studied this long-recognized but unexplained relationship in root hairs of the legume Vicia hirsuta by a variety of microscopic techniques. Using rhodaminyl lysine phallotoxin, and antitubulin antibodies, root hairs are shown to contain axial bundles of F-actin and a complex microtubular system. To the basal side of the nucleus the microtubules are cortical and net axial but in the region between nucleus and tip the arrangement is more complicated. Electron microscopic thin sections demonstrate that internal bundles of microtubles exist in addition to the plasma membrane-associated kind. Computerized deblurring of through-focal series of antitubulin stained hairs clarifies the three-dimensional organization: bundles of endoplasmic microtubules progress from the nuclear region toward the apical dome where they can be seen to fountain out upon the cortex.The relationship between nucleus and tip can be uncoupled with antimicrotubule herbicides. Time lapse video microscopy shows that these agents cause the nucleus to migrate toward the base. This contrary migration can be inhibited by adding cytochalasin D, which fragments the F-actin bundles.It is concluded that microtubules connect the nucleus to the tip but that F-actin is involved in basipetal migration as is known to occur when symbiotic bacteria uncouple the nucleus from the tip.
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  • 20
    ISSN: 0886-1544
    Keywords: capping ; concanavalin A ; glycoprotein ; membrane-cytoskeletal interactions ; thymocyte ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two major rat thymocyte surface glycoproteins, the leucocyte-common (L-C) antigen and the leucocyte sialoglycoprotein (LSGP), were induced to cap independently, using the specific monoclonal antibodies OX-1 and W3/13, respectively, and an appropriate fluorescently labeled second antibody layer. The caps were subsequently isolated from detergent extracted cells by a procedure involving gentle shearing.TRITC-phalloidin staining of the isolated caps demonstrated the presence of F-actin within these structures, and lectin-affinity staining after fractionation on SDS polyacrylamide gels revealed the presence of a concanavalin A (Con A) binding protein of relative molecular weight (Mr) 205,000, gp205, in both the L-C antigen and LSGP caps, but absent from the detergent-insoluble residue isolated from unchallenged cells. These results suggest that gp205 may be involved in the association of cross-linked glycoproteins with the cytoskeleton during capping.
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  • 21
    ISSN: 0886-1544
    Keywords: vimentin ; hereditary disease ; proteolysis ; serum ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Skin fibroblasts from two siblings with giant axonal neuropathy (GAN) were examined by both biochemical and immunocytochemical studies. The presence of intermediate filaments (IF) characteristic of these cells was affected by the growth conditions. Immediately after plating and during the following 24 hours the majority of the cells contained an IF “bundle”; however, after 4-6 days in culture only a minority of the cells retained this structure. We present evidence that trypsinization but not serum concentration is likely to influence the formation of the “bundle.” The results indicate that the formation of the “bundle” may result from a defective association or relationship between the cytoskeleton and the plasma membrane.
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 44-54 
    ISSN: 0886-1544
    Keywords: monoclonal antibody ; phosphoproteins ; basal bodies ; morphogenesis ; Paramecium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The presence of phosphorylated proteins associated with microtubule organizing centers in tissue culture cells during mitosis has been demonstrated by the use of monoclonal antibodies raised against mitotic HeLa cells [Vandre et al., Proc. Natl. Acad. Sci. U.S.A. 81:4439-4443, 1984]. We report here that in Paramecium two of the mitosis specific antibodies, MPM-1 and MPM-2, decorate throughtout the cell cycle all the microtubule organizing centers (MTOCs) located in the cortex and in the oral apparatus (gullet). Immuno-electron microscopy showed that these antibodies labeled the electron-dense material surrounding basal bodies from which several microtubule networks as well as kinetodesmal fibers originate. During mitosis, these antibodies also stained other cortical cytoskeletal structures, the kinetodesmal fibers (MPM-1 and MPM-2) and the epiplasm (MPM-1). Among the different polypeptides recognized by the antibodies on immunoblots, three major ones of 60, 63, and 116 kDa were found to be common to the cortex (where several thousand ciliary basal bodies are anchored) and the oral apparatus (which comprises several hundred basal bodies around which various arrays of cytoplasmic microtubules are organized). Alkaline phosphatase treatment abolished the immunoreactivity of the polypeptides and the labeling observed by immunofluorescence. These results demonstrate that phosphorylated proteins are associated with all the known active microtubule organizing centers present in the cortex throughout the cell cycle of Paramecium. Furthermore they indicate that in Paramecium phosphorylation of proteins could also be involved in the cell cycle dependent dynamics of cortical cytoskeletal structures other than microtubules.
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  • 23
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    Cell Motility and the Cytoskeleton 8 (1987), S. 68-75 
    ISSN: 0886-1544
    Keywords: dynein ; flagella ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mutants with outer dynein arm defects or deficiencies all show a major reduction in beat frequency to about half the normal value; some of these mutants show an additional decrease in sliding velocity associated with reduced shear amplitude and an additional reduction in beat frequency, as well as other more minor modifications of the normal forward mode bending pattern. New mutants (ida98, pf30), which appear to be deficient in a subset of inner dynein arms show a reduction in sliding velocity that is primarily associated with a reduction in shear amplitude, with only a small reduction in beat frequency. These differences in motility phenotype between inner and outer dynein arm mutants suggest that inner and outer dynein arms may have distinct functions. The relatively large decrease in sliding velocity associated with partial loss of inner arms is consistent with earlier observations on pf23, a nonmotile mutant lacking inner arms, suggesting that inner arms may have an essential function in motility. The ability to generate reverse mode bending patterns is retained in some inner or outer dynein arm mutants, but appears to be decreased in those mutants which show reduced shear amplitude for the forward mode bending pattern.
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  • 24
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 85-90 
    ISSN: 0886-1544
    Keywords: blue damselfish ; motile iridophore ; microtubule ; colchicine ; EHNA ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Iridophores of the blue damselfish, Chrysiptera cyanea, responded to the sympathetic substance, norepinephrine by a shift towards longer wavelengths of the spectral peak of the light reflected by stacks of light-reflecting platelets (“coloring response”). All antimitotic reagents tested, i.e., colchicine, vinblastine, and podophyllotoxin, inhibited the response reversibly, while an actin inhibitor, cytochalasin B, did not. Erythro-9-[3-(2-hydroxynonyl)]adenine (EHNA), a dynein ATPase inhibitor, also blocked the iridophore response effectively. These results indicate that the tubulin-dynein system may be involved in the motility of iridophores, which is regarded as the simultaneous alteration of the distance between adjacent reflecting platelets within the cells.
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  • 25
    ISSN: 0886-1544
    Keywords: cell motility ; sensory transduction ; slime mold ; pseudopod formation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In an aggregation territory of Dictyostelium discoideum, outwardly moving, nondissipating waves of the chemoattractant cAMP sweep across each ameba. At the front of each wave, an ameba experiences an increasing temporal and a positive spatial gradient of cAMP. At the back of a wave, an ameba experiences a decreasing temporal and a negative spatial gradient of cAMP. Employing a perfusion chamber, we have mimicked the temporal dynamics of these waves in the absence of a spatial gradient and demonstrated that the frequency of lateral pseudopod formation and the frequency of turning are dramatically affected by the direction and dynamics of the temporal gradient. In addition, since an ameba will move in a directed fashion up a shallow, nonpulsatile gradient of cAMP, we also mimicked the increasing temporal gradient generated by an ameba moving up a shallow spatial gradient. The frequency of lateral pseudopod formation and the frequency of turning were depressed. Together, these results demonstrate that amebae can assess the direction of a temporal gradient of chemoattractant in the absence of a spatial gradient and alter both the frequency of pseudopod extension and turning, accordingly. Although these results do not rule out the involvement of a spatial mechanism in assessing a spatial gradient, they strongly suggest that the temporal dynamics of a cAMP wave or the temporal gradient generated by an ameba moving through a spatial gradient may play a major role in chemotaxis.
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  • 26
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    Cell Motility and the Cytoskeleton 8 (1987), S. 61-67 
    ISSN: 0886-1544
    Keywords: platelets ; cytoskeleton ; vimentin ; microtubules ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Human and bovine platelets contain a 58,000-dalton vimentinlike protein that cross-reacts with antivimentin antibody. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blots indicate that this protein is present in whole platelet lysates and triton insoluble cytoskeletons. Transmission electron microscopy of platelets reveals an isotropic network of individual intermediate filaments distributed throughout the platelets. High salt, triton extracted, glutaraldehyde and tannic acid fixed platelets reveal 10-nm filaments that can be seen to form a peripheral ring, as well as an isotropic network in the body of the cells. Indirect immunofluorescence of resting and spread platelets demonstrates a circumferential staining pattern close to the cell membrane, with additional fibrillar staining throughout the platelets. Our data suggest that the 58,000-dalton vimentinlike protein may be associated with the microtuble coil and the plasma membrane, and may thus help to maintain the resting platelet's discoid shape.
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  • 27
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 28
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    Cell Motility and the Cytoskeleton 8 (1987), S. 76-84 
    ISSN: 0886-1544
    Keywords: flagella ; starfish spermatozoon ; proximal centriole ; bend direction ; bend asymmetry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Since starfish spermatozoa have spherical heads, it is not easy to determine the topographical relationship of the axoneme to the directions of the flagellar bends, the principal, and the reverse bends as defined by Gibbons and Gibbons [J. Cell. Biol. 1972, 63:970-985]. The demembranated spermatozoa are known to take the quiescent “cane” shape with a sharp principal bend at the proximal region of the flagellum in the presence of high concentration of Ca2+. When such spermatozoa were placed on a grid for electron microscopy, fixed with osmic acid vapor, washed with distilled water, and negatively stained with urany1 acetate, the head of the spermatozoon was disrupted and dispersed disclosing the proximal centriole at at the proximal end of the flagellum. The proximal centriole was always found on the concave side of the “cane” -shaped flagella. Electron microscopy of the serial thin sections of intact and demembranated spermatozoa revealed that the doublet microtobules numbers 5 and 6 were contained in the convex edge of the principal bend.
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  • 29
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    Cell Motility and the Cytoskeleton 8 (1987), S. 227-237 
    ISSN: 0886-1544
    Keywords: Vimentin ; tubulin ; lymphocytes ; stimulation ; mitosis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have used double immunofluorescence and electron microscopy to examine the distribution of tubulin and vimentin during the stimulation of mouse splenic lymphocytes by the mitogen concanavalin A. In unstimulated cells, vimentin forms a filamentous network partially coincident with the radial pattern of microtubules. In stimulated cells, the numbers of microtubules assembled from the centrosome. When these cells enter mitosis, vimentin is arranged into a filamentous cage enclosing the mitotic apparatus. During cytokinesis, the polar centrosomes are observed at a position adjacent to the midbody and vimentin is detected as an aggregate, similar to that seen prior to mitosis, close to the centrosome in each daughter cell. Using several agents, such as colchicine, colcemid, nocodazole, and taxol, which affect microtubule assembly, we have observed that the vimentin system, although closely related spatially to the microtubule complex in lymphocytes, can still reorganize independently as these cells progress through in the cell cycle. Throughout mitogenic stimulation in the continued presence of taxol, microtubules are reorganized into a few thick bundles while the vimentin system undergoes a sequence of rearragements similar to those observed during normal stimulation. These data suggest that vimentin dynamics may be important in the progression of lymphocytes through the cell cycle in response to mitogen.
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  • 30
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    Cell Motility and the Cytoskeleton 7 (1987), S. 198-208 
    ISSN: 0886-1544
    Keywords: high-speed microcinematography ; Hemicentrotus ; primitive response ; ciliary reversal ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Transient ciliary movement during responses to electric stimulation of embryos of the sea urchin, Hemicentrotus pulcherrimus, was analyzed in terms of angular direction with a time resolution of approximately 2 ms with high-speed microcinematography. In the primitive response, which can be induced only in the early stages of development of the embryo, bending transients always started with a short pause in the middle of the effective stroke, irrespective of beat position on stimulation. In the reversal response, induced only in the late stages of development, bending transients occurred with a delay as short as some 10 ms from stimulation, and with a transient sharp deviation from the normal beat before the cilium took the position of the beginning of the recovery stroke of the reversed beat. The delay was significantly shorter at the base than at the tip, suggesting that some form of signal travels along the cilium; the speed was ten times higher than that of propagating bends in the normal beat. These facts indicate that the sensitivity to internal changes resulting from stimulation of the axoneme may vary with development, ciliary beat positions, and regions along the cilium.
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  • 31
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    Cell Motility and the Cytoskeleton 8 (1987), S. 324-332 
    ISSN: 0886-1544
    Keywords: sperm motility ; procaine ; calcium ; cAMP ; flagellum ; epididymis ; TMB-8 ; hyperactivation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Rat sperm from the cauda epididymis exhibit increased motility, longevity, and a distinct circular pattern of flagellar curvature in response to 5 mM procaine-HCI or 0.1 mM 8-(N, N-diethylamino)-octyl-3,4,5-trimethoxybenzoate (TMB-8), reagents that are thought to play a role in the immobilization of free cellular calcium. Triton X-100-extracted sperm models will exhibit the same pattern of motility and curvature as procaine- or TMB-8-activated cells, but only when calcium is removed by a strong chelating agent, and in the pesence of cAMP (3 μM). Demembranated sperm models produced from epididymal rat sperm are quiescent unless cAMP is added. In these sperm models, the presence or absence of free calcium mediates a transition in flagellar curvature. The increased activity of the procaine-treated intact cells was not accompained by a change in cellular ATP content, nor was ATP availability the limiting factor in the quiescent sperm. Therefore, the increased motility produced by procaine is probably mediated by a fall in free intracellular Ca2+ accompained by a rise in cAMP. Our finding that calcium controls the curvature of sperm flagella may explain altered patterns of flagellar beating, such as the hyperactivated motility that sperm exhibit in the female reproductive tract.
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  • 32
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    Proteins: Structure, Function, and Genetics 2 (1987) 
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 33
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 13-19 
    ISSN: 0887-3585
    Keywords: two-dimensional electrophoresis ; ethylnitrosourea ; somatic mutations ; structural variants ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The feasibility of detecting human somatic structural gene mutations by two dimensional electrophoresis has been investigated. A lymphoblastoid cell line was grown as a mass culture in the presence of ethylnitrosourea, after which cells were regrown as single cell clones. A total of 257 polypeptide spots were analyzed in gels derived from 186 clones. Four structural mutations were detected by visual analysis of the gels. Computer analysis of gels corresponding to the mutant clones was also undertaken. At a spot size threshold of 200 spots to be matched using a computer algorithm, all four mutant polypeptides were detected. These results indicate the usefulness of the two-dimensional approach for mutagenesis studies at the protein level.
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  • 34
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 1-12 
    ISSN: 0887-3585
    Keywords: protein crystallography ; protein refinement ; empirical energy simulations ; error analysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The uncertainties in the refined parameters for a 1.5-Å X-ray structure of carbon-monoxy (FeII) myoglobin are estimated by combining energy minimization with least-squares refinement against the X-ray data. The energy minimization, done without reference to the X-ray data, provide perturbed structures which are used to restart conventional X-ray refinement. The resulting refined structures have the same, or better, R-factor and stereochemical parameters as the original X-ray structure, but deviate from it by 0.13 Å rms for the backbone atoms and 0.31 Å rms for the sidechain atoms. Atoms interacting with a disordered sidechain, Arg 45 CD3, are observed to have larger positional uncertainties. The uncertainty in the B-factors, within the isotropic harmonic motion approximation, is estimated to be 15%. The resulting X-ray structures are more consistent with the energy parameters used in simulations.
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  • 35
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 20-33 
    ISSN: 0887-3585
    Keywords: calmodulin ; peptide ; calmodulin-binding peptide ; peptide design ; hydrophobic moment ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A basic, amphiphilic α helix is a structural feature common to a variety of inhibitors of calmodulin and to the calmodulin-binding domains of myosin light chain kinases. To aid in recognizing this structural feature in sequences of peptides and proteins we have developed a computer algorithm which searches for sequences of appropriate length, hydrophobicity, helical hydrophobic moment, and charge to be considered as potential calmodulin-binding sequences. Such sequences occurred infrequently in proteins of known crystal structure. This algorithm was used to find the most likely site in the catalytic (γ) subunit of phosphorylase b kinase for interaction with calmodulin (the δ subunit). A peptide corresponding to this site (residues 341-361 of the γ subunit) was synthesized and found to bind calmodulin with approximately an 11 nM dissociation constant. A variant of this peptide in which an aspartic acid at position 7 in its sequence (347 of the γ subunit) was replaced with an asparagin was found to bind calmodulin with approximately a 3 nM dissociation constant.
    Additional Material: 8 Ill.
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  • 36
    ISSN: 0887-3585
    Keywords: proteolytic cleavage ; immunological cross-reaction ; amber fragment ; temperature-sensitive mutant ; stationary growth-phase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Immunological cross-reaction was employed for identification of proteolytic fragments of E. coli RNA polymerase genered both in vitro and in vivo. Several species of partially denatured but assembled RNA polymerase were isolated, which were composed of fragments of the two large subunits, β and β′, and the two small and intact subunits, α and σ. Comparison of the rate and pathway of proteolytic cleavage in vitro of unassembled subunits, subassemblies, and intact enzymes indicated that the susceptibility of RNA polymerase subunits to proteolytic degradation was dependent on the assembly state.Using this method, degradation in vivo was found for some, but not all, of the amber fragments of β subunit in merodiploid cells carrying both wild-type and mutant rpoB genes. Although the RNA polymerase is a metabolically stable component in exponentially growing cells of E. coli, degradation of the full-sized subunits was found in two cases, i.e., several temperature-sensitive E. coli mutants with a defect in the assembly of RNA polymerase and the stationary-phase cells of a wild-type E. coli. The in vivo degradation of RNA polymerase was indicated to be initiated by alteration of the enzyme structure.
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  • 37
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 54-63 
    ISSN: 0887-3585
    Keywords: domain association ; protein folding ; viscosity dependence ; solvent effects ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The equilibria and kinetics of ureainduced unfolding and refolding of the α subunit of tryptophan synthase of E. coli have been examined for their dependences on viscosity, pH, and temperature in order to investigate the properties of one of the rate-limiting steps, domain association. A viscosity enhancer, 0.58 M sucrose, was found to slow unfolding and accelerate refolding. This apparently anomolous results was shown to be due to the stabilizting effect of sucrose on the folding reaction. After accounting for this stabilization effect by using linear free-energy plots, the unfolding and refolding kinetics were found to have a viscosity dependence. A decrease in pH was found to stabilize the domain association reaction by increasing the refolding rate and decreasing the unfolding rate. This effect was accounted for by protonation of a single residue with a pK value of 8.8 in the native state and 7.1 in the intermediate, in which the two domains are not yet associated. The activation energy of unfolding is 4.8 kcal/mol, close to the diffusion limit. The negative activation entropy of unfolding, -47 cal/deg-mol, which controls this reaction, may result from ordering of solvent about the newly exposed domain interface of the transition state. These results may provide information on the types of noncovalent interactions involved in domain association and improve the ability to interpret the folding of mutants with single amino-acid substitutions at the interface.
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  • 38
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 34-41 
    ISSN: 0887-3585
    Keywords: adrenergic receptors ; affinity chromatography ; electron microscopy ; oligomeric structure ; target size analysis ; HPLC digest mapping ; receptor evolution ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We have characterized the structure of purified beta-adrenergic receptors by a combination of photoaffinity labeling, high performance liquid chromatography (HPLC)-tryptic mapping, CNBr fragmentation, target size analysis, and electron microscopy of purified receptor molecules. Guinea pig lung beta-adrenergic receptors purified by affinity chromatography, ion exchange chromatography, and HPLC size exclusion chromatography or photoaffinity labeled with [125]-iodocyanopindolol diazirine displayed mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) that corresponded to Mr = 68,000. Purified, radioiodinated guinea pig lung beta-receptors were subjected to complete trypsin digestion and subsequent reverse-phase HPLC analysis, which revealed nine peptides. Active site labeling and tryptic digestion of partially purified hamster lung beta-receptors produced one peptide, whereas CNBr digestion of the same material produced two labeled fragments, yielding information about the location of the active site within the primary sequence. Purified guinea pig lung receptors were examined with transmission electron microscopy. Electron micrographs revealed slightly asymmetric, rod-shaped structures with an average length of 13 nm and width of 3.4 nm. Many receptors were arranged as apparent dimeric structures. These findings confirm data obtained from target size analysis of guinea pig lung beta-receptors in situ which suggest that receptors may exist as oligomeric arrays in the native membrane. Taken together, these data provide information about putative functional domains of the beta-adrenergic receptor and its quaternary structure.
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  • 39
    ISSN: 0887-3585
    Keywords: intrahelical ion pairs ; frequency of ion pairs in exposed helices ; alpha-helix stabilization ; protein tertiary structure stabilization ; protein-folding pathway ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A survey of 47 globular proteins was made to determine the probability of occurrence of ion pairs separated by 1, 2, 3, … and 8 residues in the alpha helices. As a control, the probability of occurrence of like charged pairs was also determined. The survey showed that ion pairs of the type i, i±3 and i, i±4 are the most predominant. Such a preference was not observed for like charged pairs. The observed frequency of ion pairs is significantly greater than their expected frequency. The normalized frequencies of occurrence of the ion pairs were also found to increase generally with the helix length. These results indicate that the ion pairs may contribute to the stability of solvent-exposed alpha helices. Since the stabilization of protein secondary structure, these results may throw light on the mechanism of protein folding.
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  • 40
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    Proteins: Structure, Function, and Genetics 2 (1987) 
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 41
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 79-80 
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 42
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 72-77 
    ISSN: 0887-3585
    Keywords: CO equilibrium constants ; des-(Arg 141α)HbA ; heme proteins ; high-affinity state ; kinetics ; ligand binding ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A few years ago we reported that histidine (HC3) 146β plays a major role in the pH-dependent propeties of the R-state of human hemoglobin, accounting for close to 50% of the R-state Bohr effect. We have extended these studies by examining the role of arginine 141α, another group known to affect the overall Bohr effect. We have compared the pH dependencies of the rate constants for the dissociation and combination of the fourth carbon monoxide molecule, I4 and I′4, respectively, for native hemoglobin A (HbA) and a control reconstututed HbA, and des-(Arg 141α) HbA, the hemoglobin molecule resulting from the enzymatic removal of the C-terminal arginine of the α-chain of human Hb. From these kinetic contants the pH dependence of L4, by about 80% between pH 6 and 8, where the aldkaline Bohr effect normally occurs, The sum of the effects of the removal of His 146β and of Arg 141α is grater than 100%. This suggests that at least one of these modifications altrs the contrubutions of other residues of this Bohr effect.
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  • 43
    ISSN: 0887-3585
    Keywords: hybrid immunologlobulin ; compatible plasmids ; transfection ; mouse IgG1 ; mouse IgG2a ; dansyl ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We have produced a series of hybrid IgG1-IgG2a mouse immunoglobulins with identical light chains (L) and variable regions to facilitate the identification of structural features associated with functional differnces between immunoglobulin isotypes. Hybrid heavy chain (H) constant region gene segments were generated by genetic recombination in Escherichia coli between plasmids carrying mouse γ1 and γ2a gene segments. Crossovers occured through out these segments although the frequency was highest in regions of high nucleotide sequence homology. Eleven variant immunoglobulins produced by transfected hybridoma cell lines are assembled into H2L2 tetramers and properly glycosylated. In addition, all 11 immunoglbulins have identical antigen combining sites specific for the fluorescent hapten ε-dansyll-L-lysine. Protein A binding was used as probe of the structural integrity of the Fc portion of the variant antibodies. Differeneces in protein A binding between IgG1 and IgG2a appear to be due to amino acid differances at postions 252 (Thr→Met) and 254 (Thr→Ser) of the heavy chain (EU numbering).
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  • 44
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 111-117 
    ISSN: 0887-3585
    Keywords: crystallography ; antigen ; glycoprotein ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Neuraminidases from different subtypes of influenza virus are characterized by the absence of serlogical cross-reactivity and an amino acid sequence homology of approximately 50%. The three-dimensional structure of the neuraminidase antigen of subtype N9 from an avian influenza virus (A/tern/Australia/G70c/75) has been determined by X-ray crystallography and shown to be folded similarly to neuraminidase of subtype N2 isolated from a human influenza virus. This result demontrates that absence of immunological cross-reactivity is no measure of dissimilarity of polypeptide chain folding. Small differences in the way in which the subunits are organized around the molecular fourfold axis are observed. Insertions and deletions with respect to subtype N2 neuraminidase occur in four regions, only one of which is located within the major antigenic determinants around the enzyme active site.
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  • 45
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 90-110 
    ISSN: 0887-3585
    Keywords: compact units ; coefficient of compactness ; folding intermediates ; protein structural hierarchy ; primitive units ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The coefficient of compactness was recently introduced and used to locate domains in lysozyme and ribonuclease (Zehfus and Rose: Bio-chemistry 25:5759-5765, 1986). Nineteen additional proteins now have been analyzed by using this measure. Complete listings of compact units and plots showing their hierarchic organization are presented for all twenty-one proteins. Large compact units correspond well to protein domains; however, many smaller compact structures of equal or better compactness are also found. Since small compact units could represent subdomains or protein-folding intermediates, their structural composition is further examined.
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  • 46
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 118-129 
    ISSN: 0887-3585
    Keywords: homologous proteins ; hydropathy index ; chain flexibility ; α/β barrels ; tryptophan ; synthase aplha subunit ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The amino acid sequences of the α subunits of tryptophan synthase form ten different microorganisms were alingned by standard procedures. The α helics, β strands and turns of each sequence were predicted separately by two standard prediction algorithms and averaged at homologous sequence positions. Additional evidence for conserved secondary structure was derived form profiles of average hydropathy and chain flexibility values, leading to a joint prediction. There is good agreement between (1) predicted β strands, maximal hydropathy and minimal flexibility, and (2) predicted loops, great chain flexibility, and protein segments that accept insertions of various lengths in individual sequences. The α subunit is predicted to have eight repeated β-loop-α-loop motifs with an extra N-terminal α helix and an intercalated segment of highly conserved residues. This pattern suggests that the teritiary structure of the α subunit is an eightfold α/β barrel. The distribution of conserved amino acid residues and publilshed data on limited proteolysis, chemical modification, and mutagenesis are consistent with the α/β barrel structure. Both the active site of the α subunit and the combining site for the β2 subunit are at the end of the barrel formed by the carboxyl-termini of the β strands.
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  • 47
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 153-161 
    ISSN: 0887-3585
    Keywords: accessbility ; hydrophobic effect ; protein conformation ; Boltzmann statistics ; maximum likelihood ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Globular proteins fold into compact particles with interior amino acid residues shielded from the surounding aqueous environment. An early hypothesis holds that entropic hydophobic forces dirve this phenomenon. However, previous analyses based on a binary description of the accesible surfaces of amino acid residues in proteins did not support theis hypothesis. This report shows that a complete description of accessible surface areas is given by parametric distribution fuctions with three modes. The modes are formed by partitioning the available accessible surface area of the amino acids into three segments; the data for each segment are characterized by a mode-specific model. In the “repulsive” mode, probabilities of accessibility decrease exponentially with exposed surface area, as predicted by the hydrophobic hypothesis. A distinct “buried” mode is needed to account for an excess of residues at or near zero accessibility for most amino acids, consistent with the use of binary descriptions of accessibility. A third mode exists which is termed “near neutral” because it is described by a nearly uniform distribution of accessibility for the hydrophiliic amino acids. Empirical energies calculated for the repulsive mode correlate well with measured free energies of transfer of amino acids from water to organic solvents, while those from the buried mode correlate well with measured free energies of hydration of the side chains. Poor cross correlations between these energies give an explanation for the previous conflict in interpreting these data.
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  • 48
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 162-166 
    ISSN: 0887-3585
    Keywords: protein folding ; secondary structure prediction ; tertiary structure prediction ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In recent years, the protein-folding problem has attracted the attention of molecular biologists. Efforts have focused on developing heuristic and energy-based algorithms to predict the three-dimensional structure of a protein from its amino acid sequence. We have applied a series of heuristic algorithms to the sequence of human growth hormone. A family of five structures which are generically right-handed fourfold α-helical bundles are found from an investigaion of ∼108 structures. A plausible receptor binding site is suggested. Independent crystallographic analysis confirms some aspects of these predictions. These methods only deal with the “core” structure, and conformations of many residues are not defined. Further work is required to identify a unique set of coordinates and to clarify the topological alternatives available to α-helical proteins.
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  • 49
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 130-152 
    ISSN: 0887-3585
    Keywords: amino acid hydophobicity scale ; QSAR ; amino acids ; peptide side chains ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The fragment method of calculation partition coefficients (P) has been extended to include the common amino acids (AAs). The results indicate that polar and charged side chains influence the hydrophobicity of atoms in the side chain in a predictable manner. Feild effects, as evidenced through polar proximity factors and bond factors, need to be considered for accurate estimation of transfer phenomena. The calculated log P and ΔG°′ values of the 20 AAs agree well with the observed values. Pro calculates to be more hydrophilic than the observed log P. Hydrophobicity scales for peptide side chain residues are compared and evaluated in terms of suitability. Calculated π values for nonpolar side chain residures agree well with the observed values; calculated values for uncharged polar side chain residues deviate by about 0.6 log units except for Gln and Cys; and polar side chain residues with charged side chains calculate as too hydorphilic. Reasons for the differences are explored. We also suggest that tightly bound water to polar moieties in amino acids and peptides may be transferred into the octanol phase during partitioning experiments. A quantitative methodology is persented which characterizes the thermodynamic partitioning of groups and individual atoms in amino acids and proteins.
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  • 50
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    Proteins: Structure, Function, and Genetics 2 (1987) 
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 51
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 177-187 
    ISSN: 0887-3585
    Keywords: evolution ; protein structure ; nucleotide binding domain ; gene sequence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The intron/exon organization of the human gene for glycogen phosphorylase has been determined. The segments of the polypeptide chain that corresponds to the 19 exons of the gene are examined for relationships between the three-dimensional structure to the protein and gene structure. Only weak correlations are observed between domains of phosphorylase and exons. The nucleotide binding domains that are found in phosphorylase and other glycolytic enzymes are examined for relationships between exons of the genes and structures of the domains. When mapped to the three-dimensional structures, the intron/exon boundaries are shown to be widely distributed in this family of protein domains.
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  • 52
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 188-201 
    ISSN: 0887-3585
    Keywords: NMR ; NOE ; protein conformation ; structure data base ; structure fragments ; modelling ; distance matrices ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A method to build a three-dimensional protein model from nuclear magnetic resonance (NMR) data using fragments from a data base of crystallographically determined protein structures is presented. The interproton distances derived from the nuclear Overhauser effect (NOE) data are compared to the precalculated distances in the known protein structures. An efficient search algorithm is used, which arranges the distancs in matrices akin to a Cα diagonal distance plot, and compares the NOE distance matrices for short sequential zones of the protein to the data base matrices. After cluster analysis of the fragments found in this way, the structure is built by aligning fragments in overlapping zones. The sequentially long-range NOEs cannot be used in the initial fragments search but are vital to discriminate between several possible combinations of different groups of fragments. The method has been tested on one simulated NOE data set derived from a crystal structure and one experimental NMR data set. The method produces models that have good local structure, but may contain larger global errors. These models can be used as the starting point for further refinement, e.g., by restrained molecular dynamics or interactive graphics.
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  • 53
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 236-259 
    ISSN: 0887-3585
    Keywords: atomic probability distributions of proteins ; anisotropy and anharmonicity of motions in proteins ; multiple occupancy of atomic positions in proteins ; molecular dynamics simulation ; lysozyme ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Positional probability density functions (pdf) for the atomic fluctuations are determined from a molecular dynamics simulation for hen egg-white lysozyme. Most atoms are found to have motions that are highly anisotropic but only slightly anharmonic. The largest deviations from harmonic motion are in the direction of the largest rms fluctuations in the local principal axis frame. Backbone atoms tend to be more nearly harmonic than sidechain atoms. The atoms with the largest anharmonicities tend to have pdfs with multiple peaks, each of which is close to harmonic. Several model pdfs are evaluated on the basis of how well they fit probability densities from the dynamics simulations when parameterized in terms of the moments of the distribution. Gram-Charlier and Edgeworth perturbation expansions, which have been successful in describing the motions of small molecules in crystals, are shown to be inadequate for the distributions found in the dynamics of proteins. Multipeaked distribution functions are found to be more appropriate.
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  • 54
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 260-261 
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 1 Ill.
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  • 55
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    Proteins: Structure, Function, and Genetics 2 (1987) 
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 56
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 298-307 
    ISSN: 0887-3585
    Keywords: α-bungarotoxin ; neurotropism ; rhabdo-virus ; α-subunit ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Peptides corresponding to portions of loop 2 of snake venom curare-mimetic neurotoxins and to a structually similar region of rabies virus glycoprotein were synthesized. Interaction of these peptides with purified Torpedo electric organ acetylcholine receptor was tested by measuring their ability to block the binding of 125I-labeled α-bungarotoxin to the receptor. In addition, inhibition of α-bungarotoxin binding to a 32-residue synthetic peptide corresponding to positions 173-204 of the α-subunit was determined. Neurotoxin and glycoprotein peptides corresponding to toxin loop 2 inhibited labeled toxin binding to the receptor with IC50 values comparable to those of nicotine and the competitive antagonist d-tubocurarine and to the α-subunit peptides with apparent affinities between those of d-tubocurarine and α-cobratoxin. Substitution of neurotoxin residue Arg37, the proposed counterpart of the quatenary ammonium of acetylcholine, with a negatively charged Glu residue reduced the apparent affinity about 10-fold. Peptides containg the neutotoxin invarint residue Trp29 had 10- to 100-fold higher affinites than peptides lacking this residue. These results demonstrate that relatively short synthetic peptides retain some of binding ability of the native protein from which they are derived, indicating that such peptides are useful in the study of proetin interactions. The ability of the peptides to compete α-bungarotoxin binding to the receptor with apparent affinites comparable to those of other cholinergic ligands indicates that loop 2 of the neurotoxins and the strucually similar segment of the rabies virus glycoprotein act as recognition sites for the acetylcholine receptor. Invarient toxin residues Arg37 and Trp29 and their viral homologs play important, although not essential, roles in binding, possibly by interaction with complementary anionic and hydrophobic subsites on the acetylcholine receptor. The α-subunit peptide most likely contains all of the determinants for binding of the toxin and glycoprotein peptides present on the α-subunit, because these peptides bind to the 32-residue α-subunit peptides with the same or greater affinity as to the intact subunit.
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  • 57
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 308-329 
    ISSN: 0887-3585
    Keywords: conformational dynamics ; normal mode analysis ; Young's modulus ; rigid structural elements ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The normal mode analysis of conformational fluctuation is carried out for a small globular protein, bovine pancreatic trypsin inhabitor. Results are analyzed mainly to reveal the mechanical construction of the protein molecule. We take dihedral angles, including peptide ω angles, as independent variables for the normal mode analysis. There are 306 such angles in this molecule. Motions in modes with frequencies lower than 120 cm-1 are showned to involve atoms in the whole protein molecule, and spatial change of displacement vectors is continues, i.e., those of atoms near in space are similar. To quantitate the observation of the continuity, a correlation function of direction vectors of atomic displacement is calculated. From this function we define a Quantity that is interpreted as the wave length of an equivalent elastic plane wave. From this Quantity we deduce eefective young's modulus for each mode. For the mode with the lowest frequency 4.4 cm-1, it terned out to be 0.8 × 109 dyn cm-2, the value two orders magnitude softer than, for instance, α-helices. Prompted by this observation, the four lowest frequency modes and also the harmonic motions in the thermal equilibrium are analyzed further mainly to detect relatively rigid structural elements in the molecule. From this analysis emerges a mechanical picture of the protein molecule that is made up of relatively rigid elements held together by very soft parts.
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  • 58
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    Proteins: Structure, Function, and Genetics 2 (1987), S. 330-339 
    ISSN: 0887-3585
    Keywords: van der Waals radii ; conformation ; amino acid residue ; dipeptide approximation ; molecular modeling ; systematic conformationl search ; N-alkyl amino acid ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Effective van der Waals radii were celebrated in such a way that molecular models built from standard bond lengths and bond angels reproduced the amino acid conformations observed by crystallography in proteins and peptides. The celebrations were based on the comparision of the Ramachandbran plots prepared from high-resolution X-ray data of protins and peptides with the allowed φ,ψ torsional angel space for the depeptide molecular models. The celebrated radii are useful as criteria with which to filter energetically improbable conformations in molecular modeling studies of proteins and peptides.
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  • 59
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    Biological Mass Spectrometry 14 (1987) 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 60
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    Biological Mass Spectrometry 14 (1987), S. i 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 61
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Amino acids can be identified unambiguously in form of their dansylated methyl esters by combination of thin-layer chromatography on polyamide and subsequent mass spectrometry without prior substance elution from the chromatographic polyamide carrier. The evaporation intensity of the amino acid derivatives is sufficient to get excellent mass spectra with significant structural information also with very small amounts of starting material (picomole level), which guarantee a high separation power in the TLC step. Besides the methylester derivatives, in part, products additionally methyl substituted at the sulfonamide nitrogen could be separated.
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  • 62
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The simple combination of thin-layer chromatography on polyamide with subsequent mass spectrometry of the separated compounds together with the carrier material has been employed for unambiguous identification of individual dipeptides in a mixture. The dipeptides were analysed in the form of their dansyl methyl ester derivatives. The appearance of molecular ions in the electron impact mass spectra simultaneously with the ions dans-NH=CHR⌝+ indicating the corresponding N-terminal amino acid residue enables a rapid and sensitive structure elucidation of the dipeptides. The chromatography and mass spectrometry can be performed with 0.2-0.3 nmol dipeptide.
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  • 63
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    Biological Mass Spectrometry 14 (1987), S. 357-362 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several classes of environmentally significant compounds were introduced into an ion trap detector (ITD) by capillary column gas chromatography, and the performance of the device as a gas chromatography/mass spectrometry (GC/MS) system was studied. The experiments conducted included studies of the precision of selected ion monitoring (SIM) measurements, the precision of relative ion abundance measurements in full mass range scans, the sensitivity and instrument detection limits in SIM and full mass range data acquisition, and the linear range of concentration calibration. It was observed that resolution may be lost and saturation may occur under certain conditions, and that the data system can report artifact ions under these conditions.
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  • 64
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Brominated dioxins and dibenzofurans (PBDDs and PBDFs) are known contaminants in commercial fire retardant preparations. Further, they are formed in incineration processes involving polybrominated biphenyl and diphenylether fire retardants. This report presents the characterization of polybrominated dioxins and dibenzofurans. In particular, environmental monitoring methodology for PBDDs and PBDFs has been developed, and confirmation criteria for GC/MS analyses are presented.
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  • 65
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    Biological Mass Spectrometry 14 (1987), S. 473-477 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analysis of reports in the world's literature suggests that average sperm densities for groups of unselected males were relatively constant at about 108 million cells per ml prior to 1950. Subsequent to that time mean sperm densities appear to have declined. Regression analysis indicates the existence of significant negative correlations between mean sperm densities and production of synthetic organic chemicals among other parameters. Phthalate esters are one class of large volume organic chemicals that are known to disturb testicular function in laboratory animals. These compounds are also the most abundant man-made chemicals in the environment. Plots of the concentration of dibutylphthalate in the cellular fraction of ejaculates against either the sperm density or the total number of sperm for the same ejaculates gave two clusters of points. These clusters suggest the existence of two or more populations vis à vis phthalate metabolism; both of which show a negative correlation between phthalate concentration and sperm production.
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  • 66
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    Biological Mass Spectrometry 14 (1987), S. 481-485 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report a case of n-nonacosane storage disease, which went undiagnosed until the death of a 55-year-old farmer. Clinical, histological, and biochemical features are discussed. n-Nonacosane storage was identified by gas chromato-graphic-mass spectrometric analysis of different tissue extracts, n-nonacosane concentration reaching 1.2 mg g-1 of lung tissue and 0.32 mg g-1 of liver tissue. It was possible to rule out a work-induced intoxication, and n-nonacosane storage appeared to be accounted for by a lifelong, heavy consumption of unpeeled apples and Brussels sprouts.
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  • 67
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new technique known as thermally-assisted fast atom bombardment (TA-FAB) has been applied to the analysis of a series of cyclic tetrapeptide mycotoxins in order to demonstrate the usefulness of the method for structural elucidation. TA-FAB uses saturated aqueous solutions of highly hydroxylated compounds, such as fructose, as alternatives to the usual viscous liquid matrices employed in conventional FAB. During the TA-FAB analysis, the probe tip is resistively heated causing diffeiences to occur in the desorption profiles for the analyte and the matrix ions enabling an optimization for analyte desorption as a function of temperature. In this study, direct comparisons are made between TA-FAB, conventional FAB, and electron impact ionization for the analysis of the Helminthosporium carbonum mycotoxins at the 1.5 μg level. The results demonstrate the superior capacity of TA-FAB to provide both molecular weight confirmation and significant fragmentation to aid in the structural elucidation of these important biomolecules.
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  • 68
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    Biological Mass Spectrometry 14 (1987), S. 517-521 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three glutathione conjugates of acetaminophen were characterized by fast atom bombardment/mass spectrometry (FAB/MS) and fast atom bombardment/mass spectrometry/mass spectrometry (FAB/MS/MS). The conjugates, 3-(glutathion-S-yl)acetaminophen, 3-(glutathion-S-yl)diacetaminophen and 3-(diglutathion-S-yl)diacetaminophen showed intense [MH]+ ions at m/z 457, 606 and 911, respectively. Only 3-(glutathion-S-yl)acetaminophen showed any fragmentation by FAB/MS. Structurally characteristic fragmentation was observed with all three conjugates when the [MH]+ ions were collisionally activated. The loss of the glycine (GLY) and glutamic acid (GLU) moieties indicated the presence of at least one glutathione (GSH) group. Multiple losses, some of which could only occur via cleavages in both GSH moieties, were observed with the diglutathione conjugate.
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  • 69
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    Biological Mass Spectrometry 14 (1987), S. 549-553 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A GC-MS procedure has been developed for the quantitation in plasma and urine of rimantadine, an antiviral drug effective against type A influenza. The assay utilizes selective ion monitoring, methane negative ion chemical ionization (NCI) and stable isotope dilution. Sensitivity to NCI is effected by derivation of rimantadine with pentafluorobenzoyl chloride. The method has been used to quantitate plasma concentrations of rimantadine over a range from 4.2 ng/ml to 416 ng/ml, and urinary concentrations of rimantadine over a range of 21 ng/ml to 2077 ng/ml.
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  • 70
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    Biological Mass Spectrometry 14 (1987), S. 127-129 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described to assign the positional series of methylene interrupted polyenoic acids, in complex mixtures, isolated from hydrolysed lipid extracts. It entails a simple comparison of the intensities of three ions of m/z 108, 150 and 192.
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  • 71
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The behaviour of 1,1·,1″-phosphinothioylidinetrisaziridine (thiotepa) in water and aqueous salt solution of various acidity was studied by field ionization mass spectrometry (FI-MS), TLC and potentiometric titration. The rate of thiotepa hydrolysis increased with increasing thiotepa, or sodium chloride concentration, and with decreasing pH. As hydrolysis products of thiotepa, mono- and dichloro derivatives formed in neutral, salt-containing and acidic solution, tepa, and products formed by P—N bond cleavage and release of aziridine have been identified.
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  • 72
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methodology for the qualitative and quantitative analysis of the anthelmintic fenbendazole and its metabolites in goat feces using electron impact (EI)/direct exposure probe (DEP)/mass spectrometric (MS) and tandem mass spectrometric (MS/MS) techniques is presented. Analyses were conducted on extracts from spiked feces and feces from animals treated per os with 5 mg fenbendazole/kg, with samples being collected at zero time and at twelve hour intervals for 144 h. The results of the EI/DEP/MS quantitation of these samples are compared to those for the same samples analysed by high pressure liquid chromatography (HPLC). Mass spectral data for fenbendazole and its metabolites are presented and the advantages of the use of EI/DEP/MS and/or DEP/MS/MS over HPLC are discussed. This methodology may be used as a confirmatory method for the HPLC analysis of fenbendazole and its metabolites or may be used as a method in its own right for the rapid qualitative and quantitative analysis of these compounds.
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  • 73
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Known and possible phenolic and primary and secondary amine metabolites of lidocaine were added to urine from drug-naive rats. These metabolites were derivatized in this aqueous medium by acetylation with acetic anhydride or by pentafluorobenzoylation with pentafluorobenzoyl chloride. The derivatives were simultaneously extracted into an organic solvent. The products were separated by gas chromatography (flame ionization detection for acetates and electron-capture detection for pentafluorobenzoates) and identified by combined gas chromatography/mass spectrometry. Mass spectral fragmentation pathways were readily deduced; diagnostic fragment ions were identified and were valuable for characterization purposes. Structural isomers could be distinguished on the basis of their GC retention times.Extractive derivatization using pentafluorobenzoyl chloride is an attractive analytical procedure for the identification of phenolic and dealkylated metabolites of lidocaine.
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  • 74
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 75
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    Biological Mass Spectrometry 14 (1987), S. 213-220 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermospray HPLC/MS analysis of the metabolites of arachidonic acid proved to be sensitive and specific. The compounds included were hydroxy-fatty acids (5-HETE, 12-HETE, and 15-HETE) and prostaglandins PGD2, PGE2, PGF2α, PGA2, PGA1, TXB2, and 6-Keto-PGF1α. Thermospray HPLC/MS analysis allows for simultaneous monitoring of each compound without the need for additional sample preparation or derivatization. The thermospray spectra for the metabolites exhibited [M + NH4]+ ions and fragment ions because of sequential loss of equivalents of H2O. HPLC/MS showed detection limits in the 0.5 to 5 ng range when using multiple ion detection for most of the metabolites. Post-column derivatization of these metabolites using trimethylanilinium hydroxide (TMAH) to form the methyl esters is also presented. This derivatization resulted in a gain in ion current by a factor of 3-6 for most compounds while adding potential specificity to the analysis. The thermospray spectra of the derivatives were nearly identical to the spectra of the free acid except the peaks were incremented by 14 daltons due to the methyl ester formation. The derivatization of the carboxylic acid group proved to be complete under thermospray conditions producing the maximum ion current and causing no compromise in operation of the interface.
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  • 76
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    Biological Mass Spectrometry 14 (1987), S. 649-651 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The identified urinary metabolites of male rats exposed to indan are: 1- and 2-indanone; 1-, 2- and 5-indanol; 2-and 3-hydroxyl-1-indanone; and cis- and trans-indan-1,2-diol. Indan causes kidney damage in male rats in a manner similar to the cyclic hydrocarbons cis- and trans-decalin and JP-10. Lesions produced by indan occur only in male rats and not in female or control rats.
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  • 77
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dinucleoside monophosphates bearing usual protecting groups at the exocyclic amino functions of the heterocyclic bases, the 5′-hydroxy group, the phosphate moiety and the O-6-position of the guanine ring have been analysed by FAB mass specrometry in the negative ion mode. These non-charged key intermediates for oligodeoxynucleotide synthesis exhibit very simple spectra in the mass range of m/z 400-1500 using tetra-ethylene glycol as matrix. Most of the observed ions could easily be assigned. Apart from deprotonated molecular ions sequence specific ions arising from C-O-P bond cleavage and ions derived from loss of protecting groups were observed. The simplicity of spectra interpretation makes FAB mass spectrometry to a rapid and valuable tool for unambiguous identification of dimeric synthons for oligonucleotide synthesis.
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  • 78
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    Biological Mass Spectrometry 14 (1987), S. 141-142 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 79
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    Biological Mass Spectrometry 14 (1987), S. 131-140 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mixtures of both synthetic and naturally occurring (human plasma) cholesteryl esters have been examined by capillary gas chromatography/mass spectrometry (GC/MS). A magnetic sector mass spectrometer was used and a variety of ionization modes were assessed with a view to obtaining structural information on intact cholesteryl esters. By employing ammonia as reagent gas, with negative ion scanning, spectra were produced from which the nature of steryl and fatty acyl moieties could be readily deduced. Analyses were performed at an ion source temperature of 300°C in order to maintain the integrity of the gas chromatographic profile. The technique described is of general use for the GC/MS analysis of steryl esters, particularly in conjunction with magnetic sector instruments.
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  • 80
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermospray spectra on a magnetic sector mass spectrometer, by definition measured at high accelerating voltages, are seen to be highly fragmented. This is rationalised in terms of the necessity to accelerate ions through a region of high pressure in the vicinity of the ion-collecting orifice at the spray volume, where ions may be energized by ion molecule collisions. In this region, a high percentage of the parent ion current is lost through the dispersion of the ion beam and by the collisional activation of molecular ions resulting in extensive fragmentation. The investigation of means by which these effects may be minimized has led to the construction of an improved sector thermospray source. Comparative results for gramicidin S demonstrate that its fragmentation is reduced and that the intensity of the protonated molecular ion is greatly enhanced.
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  • 81
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    Biological Mass Spectrometry 14 (1987), S. 183-185 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acetates of 12 positionally isomeric tetradecenols (Δ2-Δ13) have been prepared and their mass spectra measured without any prior chemical modification. Comparison of spectra of all the isomers has shown the variation in intensities of some predominant fragments with the position of the double bond on the 14 carbons chain. The mass spectra were interpreted in terms of the relative intensity ratio of the fragment ion peaks to locate the double bond positions. A procedure for elucidation of the positional isomerism of tetradecenyl acetates is given.
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  • 82
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    Biological Mass Spectrometry 14 (1987) 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 83
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    Biological Mass Spectrometry 14 (1987), S. 207-211 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eight normal subjects ingested 125 mg of p-tyramine-β,β-2H2 hydrochloride and the 3 h and following 21 h urine collections were analysed by mass spectrometry with selected ion monitoring for the deuterated metabolites: free and conjugated p-tyramine-β,β-2H2, free p-octopamine-β-2H1, free and conjugated p-hydroxyphenylacetic acid-α-2H1 and -α,α-2H2, and free p-hydroxymandelic acid-α-2H1. These metabolites accounted for 72% of the ingested label, of which conjugated p-tyramine and free p-hydroxyphenylacetic acid constituted 90%. Approximately 50% of the total deuterated tyramine and 70% of the total deuterated p-hydroxyphenylacetic acid were excreted in the first three hours, although there was considerable variation between individuals. The presence of a small amount of p-hydroxyphenylacetic acid-α-2H1 suggests that some exchange of deuterium occurred at the intermediate p-hydrophenylacetaldehyde stage.These results, based as they are on metabolites labelled with the stable isotope deuterium, ought to be more reliable than earlier studies in which unlabelled tyramine was ingested with the resultant metabolites, indistinguishable from their endogenous metabolic counterparts, being measured by fluorimetry or gas chromatography.
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  • 84
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    Biological Mass Spectrometry 14 (1987), S. 221-227 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Human exposure to aromatic amines may be monitored by measuring the amount of sulfinamide adduct bound to hemoglobin. In order to develop a sensitive and selective method for measuring aromatic amines present in low concentrations the mass spectra of the pentafluoropropionamide derivatives of a series of aromatic amines were determined under various ionization conditions. With electron ionization the aromatic amine derivatives typically yield intense molecular ions with fragmentation leading to elimination of C2F5 and COC2F5. Higher molecular weight polycyclic aromatic amines, e.g., 6-aminochrysene, give prominent molecular ions as well as intense ions corresponding to M-174 (loss of CNHCOC2F5). With positive chemical ionization using methane as reagent gas the derivatives give protonated molecular ions as the base peaks, as well as the associated ions at M + 29 and M + 41. Negative ion chemical ionization yields, primarily, peaks corresponding to the loss of HF from the molecular anions. Negative ion chemical ionization with selected ion monitoring is generally more suitable than positive chemical ionization or electron ionization for the quantitative analysis of aromatic amines present in biological samples in the mid femtomolar range. Exposure of human subjects to aromatic amines was determined via basic hydrolysis of the isolated sulfinic acid amide hemoglobin adducts. Analysis of the derivatized extracts by gas chromatography/negative ion chemical ionization/mass spectrometry demonstrated the presence of aniline, ortho-, meta-, and para-toluidine, 2-naphthylamine, and 4-aminobiphenyl. The hemoglobin adduct levels of these amines in both cigarette smokers and nonsmokers were determined. The mean values of the adduct levels of ortho- and para-toluidine, 2-naphthylamine, and 4-aminobiphenyl were higher in smokers than in nonsmokers, while the mean adduct values of aniline and meta-toluidine were similar in both groups. Adducts of 2-, 3-, 4-ethylaniline, 2,3-, 2,4-, 2,5-, 2,6-dimethylaniline, and 3-aminobiphenyl have been detected in smokers' blood. 1-Aminoanthracene, 9-aminophenanthrene, and 6-aminochrysene have not been detected. GC/MS procedures were also used to determine the extent of binding of aniline-2,3,4,5,6-d5 to hemoglobin in rats administered aniline-d5.
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  • 85
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    Biological Mass Spectrometry 14 (1987), S. 479-479 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 86
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The single dose pharmacokinetics of deuterium-labelled cannabinol (2H2-CBN) were evaluated in six male cannabis users with different degree of abuse after smoking an average dose of 19 mg and after intravenous administration of 20 mg CBN. Plasma levels were measured for up to 72 h with selected ion monitoring by GC/MS using 2H7-CBN as internal standard. The systemic availability of smoked CBN was found to be 39 ± 26% (min-max 6-65%). The mean plasma clearance was 19.1 ± 2.6 ml min-1 kg-1 and the volume of distribution was determined to 50 ± 23 1 kg-1. The apparent terminal half lives for CBN were 32 ± 17 h and 43 ± 29 h after intravenous administration and smoking, respectively.
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  • 87
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    Biological Mass Spectrometry 14 (1987), S. 533-534 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 88
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    Biological Mass Spectrometry 14 (1987), S. 523-531 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatization of prostaglandins and thromboxane B2 using diethyl amino ethyl chloride and diethyl amino ethyl bromide improved thermospray HPLC/MS sensitivity. The derivatization was evaluated for prostaglandin A1, A2, D2, E2, F1α, F2α, and thromboxane B2. The derivatization reaction, thermospray operating conditions, and mode of detection were optimized to produce the most intense [M + H]+ or [M - H]- ions for the derivative. Derivatization was better than 99% complete in 1 hour at 75°C. No thermal degradation of the prostaglandins was observed. Positive thermospray ionization proved the mode most sensitive, enabling detection from 10 to 300 pg of each prostaglandin under multiple ion detection. The thermospray spectra exhibited intense [M + H]+ ions for the derivative with a few fragment ions from sequential losses of water from the [M + H]+ ion. Detection of a prostaglandin metabolite in plasma over the concentration range from 3 ppm to 30 ppb was possible using this derivatization.
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  • 89
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas chromatographic and mass spectrometric properties of leukotriene B4, 20-hydroxy-leukotriene B4 and 20-carboxy-leukotriene-B4 were investigated as their methyl ester trimethylsilyl, methyl ester allyldimethylsilyl and methyl ester tert-butyldimethylsilyl ethers. The gas chromatographic properties of the trimethylsilyl and tert-butyldimethylsilyl ether derivatives were good with respect to peak shape and sensitivity, whereas the allyldimethylsilyl ether derivative gave a lower sensitivity. The sensitivity defined as the quantity that could be passed through the gas chromatographic column.The three derivatives showed a mass spectrometric fragmentation pattern with cleavage of the C12—C13 bond as an important feature. Particularly, the allyldimethylsilyl ether derivative of the three compounds studied exhibited a high tendency for C12—C13 bond cleavage resulting in a fairly intense ion at m/z 435. However, the mass spectra indicated multiple fragmentation pathways due to the presence of double bonds, leading to decreased intensities of the high mass ions. A quantitative analysis by selected ion monitoring of the most intense high mass ions in the respective mass spectrum demonstrated that neither derivative would allow measurements in the low picogram range. Catalytic hydrogenation of the double bonds was performed and the methyl ester trimethylsiyl, methyl ester allyldimethylsilyl and methyl ester tert-butyldimethylsilyl ether derivatives of the reduced compounds were prepared. Saturation of the double bonds increased the gas chromatographic sensitivity for the three derivatives as well as the intensities of the high mass ions in their mass spectra. The high sensitivity that can be obtained by measurement of such high mass ions was demonstrated by quantification of leukotriene B4 in lung tissue samples by selected ion monitoring.
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  • 90
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    Biological Mass Spectrometry 14 (1987), S. 355-355 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 91
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    Biological Mass Spectrometry 14 (1987), S. 363-367 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The indoor air quality of the offices of smokers and nonsmokers was surveyed for volatile organic compound identities and concentrations. These results were examined to determine whether environmental tobacco smoke contamination could be distinguished from airborne pollutants outgassing from other sources. It was not possible to positively attribute volatile organic contaminants to environmental tobacco smoke. It was possible to distinguish between smokers' and nonsmokers' offices by determining airborne nicotine levels.
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  • 92
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxygen-enhanced negative chemical ionization MS is sensitive and specific for the detection of polychlorinated biphenyls (PCBs) without isobaric interferences (qualitative or quantitative) from congeners of higher levels of chlorination. The collision-induced dissociation (CID) spectra of the [M - Cl + O]- ion of 40 PCB congeners have been acquired on a triple quadrupole mass spectrometer.Qualitative relationships between structure of the congener and its CID spectrum suggest that reliable identification of PCB congeners is possible even where capillary column gas chromatographic separation is incomplete. Congeners with hydrogen atoms located para and meta to the biphenyl linkage show most abundant collision-induced loss of HCl, whereas congeners with a penta-chloro phenyl ring show least CID loss of HCl. Congeners IUPAC 105 and 121 have CID spectra suggesting a pathway for sequential loss of HCl and CO neutrals during the collision-induced dissociation of the [M - Cl + O]- ion of these molecules. Unambiguous identification of PCB congeners in natural materials will require a complete set of pure, synthetic PCB congeners: identification problems are illustrated using an extract of Northern Shark (dogfish) liver oil.
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  • 93
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    Biological Mass Spectrometry 14 (1987), S. 535-541 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A moving belt interface was used to identify budesonide metabolites, obtained from rat and mouse liver incubations, by liquid chromatography/mass spectrometry (LC/MS). The metabolites were separated on a small-bore C18 column with an ethanol/water gradient as mobile phase at a flow rate of 0.2 ml min-1. A spray device was used for deposition of the aqueous solvent on to the belt. Chemical ionization mass spectra were obtained with methane as the reagent gas. Deuterium-labelled budesonide, which was used to facilitate metabolite identification by the isotope cluster technqiue, was found to be slightly separated from the unlabelled analogue on the LC column. Incubations were also performed under 18O2 to elucidate the mechanism of a new metabolic pathway (16α, 17α-acetal splitting) and to confirm the oxidative nature of reactions leading to hydroxylated metabolites. The moving belt LC/MS technique afforded higher sensitivity, and gave more abundant MH+ ions of the compounds studied, than previously found by direct probe mass spectrometry. Phthalate ester background, partly from the polymide belt, complicated the identification of minor metabolites.
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    Biological Mass Spectrometry 14 (1987), S. 587-588 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 95
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    Biological Mass Spectrometry 14 (1987), S. 599-602 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the quantification in plasma of CP-55,940, a new non-opiate oral analgetic agent, using capillary gas chromatography/mass spectrometry. After extraction, derivation of the drug and a structural analog internal standard is carried out with trifluoracetyl imidazole. The derivative exhibited excellent gas chrornatographic properties. Electron impact yielded an abundant high mass ion whose monitoring permitted the sensitive and specific determination of CP-55,940 down to 0.5 ng ml-1.
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  • 96
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    Biological Mass Spectrometry 14 (1987), S. 613-616 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the quantification of tulobuterol in human plasma, based upon selective extraction and high resolution capillary gas chromatography-mass spectrometry. The mass spectrometric determination is based on selected ion monitoring of two fragment ions derived from the N,O-heptafluorobutyryl derivatives of tulobuterol and its internal standard, deschlorotulobuterol. The plasma work-up procedure consists of extraction of 1.0 ml alkalinised plasma with dichloromethane, back-extraction into an acidified aqueous phase, followed by a final extraction with dichloromethane after realkalinisation. The method gave interference-free and linear results. The between-assay variability is 4.7% CV at the 3.0 μg l-1 plasma concentration level. The assay permitted quantitative measurements down to 170 ng tulobuterol per litre of plasma and hence provided sufficient sensitivity for quantification of plasma levels after therapeutic doses.
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  • 97
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    Biological Mass Spectrometry 14 (1987), S. 627-632 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In phytochemical and chemotaxonomic research work mass spectrometry plays an outstandingly important role. Using gas chromatography/mass spectrometry (GC/MS) we established the chemotaxa of Tanacetum vulgare L. Chemotypes with essential oils countaining 60-90% of artemisia ketone, carveol, dihydrocarvone, myrtenol, umbellulone, terpinen-4-ol, davanone, and Tagetes species containing various essential oils can be clearly distinguished by their spectra; we examined many variations of Tagetes erecta, T. lucida, T. minuta, T. patula and T. tenuifolia. We have identified α-β-pinene-, 1,8-cineol-, linalool-, camphor-, nerol-, geraniol- and γ-gurjonene as components of Achillea distans L. Injecting the essential oil direct from the oil-secreting organs of T. minuta plants we identified using GC/MS 6-10 and 16% eugenol from the involucral bract and hypsophyll, respectively, as well as β-ocimene, dihydrotagetone, tagetone, Z- and E-ocimenones. In the course of studies on essential fatty acids Borago officinalis and Lappula squarrosa were selected from 70 species of the family Boraginaceae to obtain seed oil as a source of γ-linolenic acid, and for the PG synthesis we isolated several grams of γ-linolenic acid, as well as C18:4, i e. octadecatetraenic acid, from L. squarrosa on the basis of the mass spectra. From the seed oil of Aquilegia vulgaris C18:3 (5) from the oil of Limnanthes dougloasii C20:1 (5) and from the seed oils of Delphinium consolida and of Tropaeolum species (T. majus, T. minus, T. peregrinum) C20:1 (11) fatty acids were identified on the basis of spectra.
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  • 98
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bile from rats treated with acetaminophen was analyzed by direct injection onto a thermospray liquid chromatography/mass spectrometry (LC/MS) system. Two conjugated metabolites of acetaminophen were separated by the high-pressure liquid chromatographic system and analyzed by mass spectrometry. The conjugates were identified as the glutathione-acetaminophen conjugate and the glucuronide-acetaminophen conjugate by comparison of the chromatographic retention times and the mass spectra to that of the synthetic standards. No evidence of acetaminophen metabolites was observed when bile samples were subjected to direct analysis by fast atom bombardment mass spectrometry.
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  • 99
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    Biological Mass Spectrometry 14 (1987), S. 733-736 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
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  • 100
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Direct analysis of unpurified urine from patients with β-ketothiolase deficiency and glutaryl-coenzyme A dehydrogenase deficiency was carried out by methylation and fast atom bombardment mass spectrometry. Previously unidentified signals consistent with unusual acylcarnitines were detected. In the former disease, thermospray liquid chromatography/mass spectrometry analysis confirmed the identification of tiglylcarnitine and differentiated it from a biological isomer, 3-methylcrotonylcarnitine. In glutaric aciduria, glutarylcarnitine was confirmed by detection of glutaric acid liberated upon base hydrolysis of a purified acylcarnitine fraction. The discovery of these metabolites suggests that L-carnitine therapy might be beneficial for the enhanced excretion of toxic metabolites that accumulate in patients with these disorders.
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