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  • 1985-1989
  • 1970-1974  (2.447)
  • 1910-1914
  • 1972  (2.447)
  • Polymer and Materials Science  (2.332)
  • Ultrastructure  (115)
  • Biochemistry
Datenquelle
Materialart
Erscheinungszeitraum
  • 1985-1989
  • 1970-1974  (2.447)
  • 1910-1914
Jahr
Schlagwörter
  • 101
    Digitale Medien
    Digitale Medien
    The structure of the organ of bellonci of the syncarid crustacean, Anaspides tasmaniae (Thomson) (1972)
    Springer
    Cell & tissue research 132 (1972), S. 431-450 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Organ of bellonci (Anaspides tasmaniae) ; Crustacea ; SPX organ ; Receptor ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The organ of Bellonci of Anaspides tasmaniae (Thomson) (Crustacea, Syncarida) is described light and electron microscopically, and a few histochemical tests are reported. Located ventrally in the eyestalk below the medulla interna, the organ is composed of a number of cavities. These are similar in structure in their contents and associated cellular components, which include two types of glia cells delimiting each cavity and the terminal parts of a few dendrites. Each dendrite usually bears two cilia, which project into the cavity where they split up into numerous branches. The organ is supplied by three nerve tracts: two from the medulla terminalis and one from the medulla interna. The sensory pore, which is innervated from the medulla interna, is not closely associated with the organ of Bellonci in Anaspides. No marked secretory activity is detectable by histochemical or ultrastructural observations. It is thought that the organ has a sensory function.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00306635
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  • 102
    Digitale Medien
    Digitale Medien
    The eyes of Creophilus erythrocephalus F. and Sartallus signatus sharp (Staphylinidae: Coleoptera) (1972)
    Springer
    Cell & tissue research 133 (1972), S. 59-86 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Compound eyes ; Coleoptera ; Ultrastructure ; Dark-light-adaptation ; Irregularities
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The structures of the eyes of two Staphylinid beetles, one large (Creophilus erythrocephalus—18 mm in length) and one small (Sartallus signatus—3 mm in length), were compared. 1. The gross structure of the two eyes is the same: a) biconvex corneal lens, b) crystalline cone of “acone type”, c) narrow crystalline thread and thickening of cone cell extensions just above the rhabdom, d) seven retinula cells plus one basal cell, and e) almost the same corneal refractive index and optical properties of the corneal cuticle. Considerable differences exist in size, shape and arrangement of rhabdom, retinula cells and their axons. The smaller size of the eye of Sartallus is caused by reduction of number of facets rather than cell size, and, in fact, retinula cells and rhabdom have been found to be larger in the smaller beetle. 2. Structural changes during dark-light-adaptation affect crystalline cone, position of screening pigment and size of intercellular spaces between the retinula cells. In the dark-adapted state the cone retracts a little and the crystalline tract becomes wider. A thickening of cone cell extensions occurs just above the rhabdom. Screening pigment migrates to a more distal position and intercellular spaces between the retinula cells considerably increase in size as compared with the light-adapted eye. 3. Both eyes are rich in irregularities. An attempt to classify anomalies of compound eyes has been made. The number of cone cells and principal pigment cells varied, in some cases, from 1–5 and 0–3 respectively. Basal retinula cells did not always contribute to the rhabdom. 4. Interferometrical observations reveal the extreme optical homogeneity of the entire corneal cuticle of the eyes of both species. No layers of different refractive index or optical separation of adjacent ommatidia can be found. The refractive index of the cornea of Creophilus is 1.469; that of Sartallus is 1.488. 5. Functional consequences of the changes which occur during dark-light-adaptation are discussed. Exposure to intense light appears to cause a rapid aging of retinula cells, which is indicated by an increase of onion- and multivesicular bodies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307068
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  • 103
    Digitale Medien
    Digitale Medien
    Die Ultrastruktur des Gabeschen Organs von Schizophyllum sabulosum L. (Diplopoda, Iuliformia) (1972)
    Springer
    Cell & tissue research 132 (1972), S. 273-285 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Diplopoda ; Organ of Gabe ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung 1. Das Gabesche Organ von Schizophyllum sabulosum ist paarig und liegt im seitlichen Clypeolabrum. Es wird von Axonen des Nervus labri medialis erreicht, der vorher Seitenzweige abgegeben hat. 2. Die Axone gehören neurosekretorischen Zellen des Protocerebrum an und enthalten Neurosekret. Die Elementargranula sind recht gleichmäßig ellipsoid, der große Durchmesser beträgt ca. 1200 Å. Die Axone enden im Organ und stellen dessen extrinsische Komponente dar. 3. Außerdem gibt es zwei intrinsische Zelltypen: 1) Drüsenparenchymzellen mit axonartigen Fortsätzen und 2) gliaartige Zellen. Die Parenchymzellen bilden Sekret in Form opaker Vakuolen, die deutlich größer als die Neurosekretgranula sind. Auffällig ist das überwiegend vesikuläre endoplasmatische Reticulum. Die Mitochondrien liegen in der Nähe von myelinähnlichen Körpern; ihre Außenmembran ist stellenweise vakuolig vorgewölbt. Die axonartigen Fortsätze enthalten viele längsorientierte Mikrotubuli. 4. Die langen Fortsätze der gliaartigen Zellen umhüllen die Parenchymzellen und die extrinsischen Axone meist in mehreren Schichten. Es gibt aber auch Bereiche, in denen vor allem die Fortsätze der Parenchymzellen und die extrinsischen Axone nackt sind. 5. Das Organ ist gegen das umgebende Hämocoel von einer dicken, lamellierten Stromahülle abgegrenzt. Auch Interzellularräume sind mit Stroma gefüllt. 6. Das Organ wird mit der Cerebraldrüse einiger Chilopoden und gewissen endokrinen Organen anderer Diplopoden und Insekten verglichen.
    Notizen: Summary 1. The paired organ of Gabe of Schizophyllum sabulosum is situated in the lateral clypeolabrum. It is innervated by axons of the medial labral nerve, which divides in several branches before reaching the organ. 2. Axons extend from neurosecretory cells of the protocerebrum and contain neurosecretory droplets, which are almost ellipsoid and about 1,200 Å in diameter. The axons terminate in the organ and constitute its extrinsic elements. 3. In addition, there are two types of intrinsic cells: (1) parenchyma cells with axon-like processes and (2) glia-like cells. The parenchyma cells produce secretory material in the form of opaque vacuoles, which are clearly larger than the neurosecretory granules. The preponderantly vesicular endoplasmic reticulum is conspicuous. Also characteristic are the mitochondria, whose superficial membranes are expanded locally, and which lie in the near vicinity of myeline-like bodies. The axon-like processes contain many microtubuli oriented in longitudinal direction. 4. The slender processes of the glia-like cells envelop both parenchyma cells and extrinsic axons usually in several layers; but there are also regions in which the processes of the parenchyma cells and, above all, the extrinsic axons are naked. 5. The organ is delimited from the surrounding hemocoele by a thick laminated stroma. Intercellular spaces are also filled with stroma. 6. The organ is compared with the cerebral gland of some chilopods and with certain endocrine organs of other diplopods and insects.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307017
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  • 104
    Digitale Medien
    Digitale Medien
    An ultrastructural study of the body wall muscles of the pentastomid Reighardia sternae dies. 1864 parasitic on the herring gull Larus argentatus pontopp (1972)
    Springer
    Cell & tissue research 130 (1972), S. 12-17 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Muscle tissue ; Pentastomid ; Body wall ; Parasite ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fine structure of the body wall muscle of the pentastomid Reighardia sternae is described. The muscle fibres are separated from one another and form two layers, circular and longitudinal. They are cross-striated with approximately 11 actin filaments surrounding each myosin filament. The T-system consists of simple in-pushings of the sarcolemma. The SR is also simple and forms both dyadic and triadic contacts with the T-system tubules and dyadic contacts with the sarcolemma. Electron-dense inclusions occur, usually in the vicinity of the Z-lines, and it is suggested that these may be composed of unsaturated lipids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00306991
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  • 105
    Digitale Medien
    Digitale Medien
    Ultrastructure de l'endomètre humain normal (1972)
    Springer
    Cell & tissue research 133 (1972), S. 47-57 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Endometrium ; Human ; Granular stroma cells ; Relaxin ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé L'ultrastructure générale des cellules K endométriales est semblable chez l'Homme, le Rat et le Singe. Mais les granulations des cellules K humaines sont plus variées que dans ces deux dernières espèces et ont certains aspects suggérant une fonction catabolique. Etant donné cet aspect catabolique et l'existence connue d'une activité phosphatasique acide de ces cellules contenant de la relaxine, les auteurs suggèrent que les cellules K pourraient être des cellules sécrétantes en involution et ques les cellules sécrétant activement la relaxine pourraient avoir un aspect morphologique quelque peu différent de celui des cellules K.
    Notizen: Summary The general ultrastructure of endometrial granular stroma cells is similar in man, rat, and monkey. But the granulations of human granular stroma cells are more various than in these two last species and have some aspects suggesting a catabolic function. With respect to this catabolic aspect and the previously shown acid-phosphatase activity of these relaxin-containing cells the authors suggest that the granular stroma cells could be involutive secretory cells and that the active relaxin-secretory cells may have some different morphological aspect.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307067
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  • 106
    Digitale Medien
    Digitale Medien
    Zur Morphologie des Ovars von Viviparus contectus (Millet 1813), (Gastropoda, Prosobranchia) (1972)
    Springer
    Cell & tissue research 133 (1972), S. 103-118 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Ovary ; Gastropoda ; Follicle cells ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Das Ovar von Viviparus contectus besteht, wie licht- und elektronenmikroskopische Untersuchungen ergeben, aus einem langen, terminal verzweigten dünnen Schlauch, dessen Wand von einem Epithel aus Oocyten in allen Entwicklungsstadien und Follikelzellen gebildet wird. Das Vorkommen von Oogonien in den Ovarien adulter Weibchen ist zweifelhaft. Die Follikelzellen sind als Begleitzellen der Oocyten im allgemeinen extrem langgestreckt. Mit ihrer Basis sitzen sie einer dünnen Basalmembran fibrillärer Struktur auf, wie sie bisher nur für Mollusken beschrieben wurde. Die Follikelzellen enthalten große Mengen von Vesikeln, einen bemerkenswert gut ausgebildeten Golgi-Apparat, spärliches rauhes endoplasmatisches Retikulum und zahlreiche heterogene cytosomale Einschlüsse. Charakteristisch für die Zellen sind außerdem in der Längsrichtung liegende cytoplasmatische Mikrotubuli und vereinzelte Kinetosomen. Obwohl keine direkten morphologischen Beziehungen zwischen Follikelzellen und Oocyten festgestellt werden konnten, wird vermutet, daß die Follikelzellen Material degenerierender Oocyten aus dem Lumen des Ovars resorbieren und speichern. Dieses kann den heranwachsenden Oocyten zugute kommen.
    Notizen: Summary The ovary of Viviparus contectus was studied light and electron microscopically. It consists of an extended and terminally branched duct, its wall being formed by oocytes of all stages and by follicle cells. The existence of oogonia in the adult females cannot be established with certainty. According to their relationship to the growing oocytes the follicle cells are in general extremely elongated. At the basis they are attached to a thin basement lamina having a fibrillar structure hitherto only known in molluscs. The follicle cells contain many vesicles, a remarkably well-developed golgi apparatus, some rough endoplasmic reticulum, and many heterogeneous cytosomes. Characteristic for these cells are also cytoplasmic microtubules oriented longitudinally along the cell axis. Kinetosomes can rarely be seen. Although there are no apparent direct interrelationships between follicle cells and oocytes, it is suggested that they are engaged in resorbing material of degenerating oocytes from the lumen of the ovary and in storing materials which may be used by the growing oocytes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307070
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  • 107
    Digitale Medien
    Digitale Medien
    The ultrastructure of neuromuscular systems in Notoplana acticola, a free-living polyclad flatworm (1972)
    Springer
    Cell & tissue research 133 (1972), S. 277-288 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Flatworm ; Muscle ; Neuromuscular junction ; Sarcoplasm ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Neuromuscular junctions in the marine polyclad flatworm, Notoplana acticola were studied with the electron microscope. Synapses were found between nerve endings and specialized extensions of the muscle cells. Characteristically these processes contained clear cytoplasm with a basal mitochondrion and numerous microtubules aligned parallel to the long axis of the extension. Sarcoplasmic diverticuli which contained the nucleus had granular cytoplasm with an assortment of membranes and organelles. We have proposed the term sarconeural junction to describe synapses between long sarcoplasmic extensions and nerve cells in flatworms as well as other animals. Tight junctions between adjacent contractile portions of muscle cells were common. As groups of cells appeared to be connected by tight junctions or shared common nerve terminals we conjectured that these formed discrete functional motor-units.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307148
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  • 108
    Digitale Medien
    Digitale Medien
    Ultrastruktur und Jodaufnahme der Schilddrüse bei Larven des Krallenfrosches (Xenopus laevis Daud.) (1972)
    Springer
    Cell & tissue research 130 (1972), S. 553-574 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Thyroid gland ; Xenopus laevis ; Iodine uptake ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Ziel dieser Untersuchung war eine physiologische Deutung der Ultrastruktur von Schilddrüsenepithelzellen bei Larven von Xenopus laevis. Dazu wurden elektronenmikroskopische Bilder mit morphometrischen Methoden quantitativ ausgewertet und die Ergebnisse mit Jodaufnahmedaten verglichen. So konnte die Aktivierung der Schilddrüse durch TSH bei kälteblockierten bzw. hypophysektomierten Tieren mit Veränderungen während der spontanen Metamorphose verglichen werden. Ihrer Ultrastruktur nach sind die Schilddrüsen blockierter Prometamorphoselarven in der Entwicklung auf ein früheres Stadium zurückversetzt. Auch zeigen hypophysektomierte Larven keine spontane Jodaufnahme. Eine einmalige TSH-Injektion läßt dann die Größe und Form der verschiedenen Organellen vorübergehend den Zustand der Kontrollen erreichen. Besonders rasch und stark sprechen einerseits die Kernstruktur, andererseits Mikrovilli und Kolloidtropfenvolumen, welche die Resorption von Thyreoglobulin charakterisieren, auf den TSH-Reiz an. Die Jodaufnahme verläuft langsamer. Auch reagieren die an der Synthese beteiligten Organellen später und schwächer. In der spontanen Metamorphose wachsen die Schilddrüsen, nach Totalvolumen, Cytoplasmavolumen einzelner Zellen und Epithelhöhe beurteilt, bis zum Ende der Metamorphose weiter und nehmen entsprechend mehr Jod auf. Ebenso wird während der ganzen Klimax die Kolloidresorption der einzelnen Zellen stärker. Aus den Ergebnissen wird geschlossen, daß die TSH-Sekretion schon in der Prometamorphose einsetzt und bis gegen Ende der Metamorphose zunimmt.
    Notizen: Summary The epithelial cells of the thyroid gland in larvae of Xenopus laevis were investigated with the electron microscope. Morphometrical methods yielded quantitative data on the morphology. The uptake of radioactive iodine was studied in order to obtain information on the physiological activity. Thus changes in the thyroid gland following the injection of TSH in tadpoles which had been hypophysectomized or blocked at low temperature were compared with the development of glands during spontaneous metamorphosis. The thyroid glands of blocked prometamorphic larvae resemble those of younger developmental stages as judged by their ultrastructure. In addition no spontaneous accumulation of iodine is observed. Following an injection of TSH the morphology of the various organelles becomes temporarily identical to that of the controls. These changes are most prominent in the nucleus as well as in the microvilli and the colloid droplets, which characterize the resorption of thyroglobulin. Only a minor effect of the TSH stimulus is found on iodine uptake and on organelles concerned with protein synthesis. During normal metamorphosis an increase is observed in the following parameters: (1) volume of the thyroid gland, (2) volume of the cytoplasm and height of single epithelial cells, (3) resorption of colloid, (4) iodine uptake. This increase persists until the end of the climax. Based on the present results TSH secretion is assumed to start in early prometamorphosis and to rise up to the end of metamorphosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307007
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  • 109
    Digitale Medien
    Digitale Medien
    Zur Morphologie und Funktion der Calcitoninzellen (C-Zellen) der Ratte (1972)
    Springer
    Cell & tissue research 134 (1972), S. 13-30 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Rat ; Thyroid C-cells ; Ultrastructure ; Tocopherol and Ubiquinone deficiency ; Substitution (d,1-α-Tocopherol, α-Tocopherolquinone)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung An der Schilddrüse von Wistar-Ratten wurde der Einfluß der Kost (Laborstandardkost, halbsynthetische-tocopherolhaltige und halbsynthetische-tocopherol-freie Kost) und der subkutanen Injektion von Tocopherol und Tocopherolchinon auf die Ultrastruktur der C-Zellen untersucht. Während nach Standardfütterung die Aktivität der C-Zellen der Norm entspricht, werden Syntheseleistung und Sekretabgabe dieser Zellelemente durch die halbsynthetische-tocopherolhaltige Kost gesteigert und im alimentären Tocopherol-Ubichinonmangel wieder gedämpft. Der elektronenmikroskopisch erkennbare Gehalt der C-Zellen an Sekretgranula entspricht der in vitro ermittelten Calcitoninaktivität. Die Beziehungen zwischen den Funktionskreisen von Thyreozyten und Calcitoninzellen werden diskutiert.
    Notizen: Summary The influence of different diets (standard laboratory diet, semisynthetic tocopherol-containing and semisynthetic tocopherol-free diet) and the influence of subcutaneous injections of tocopherol and tocopherolquinone upon the ultrastructure of the C-cells in the thyroid gland of Wistar rats were investigated. While the activity of the C-cells is quite normal after feeding a standard diet, the synthetic and secretory activities of these cells show an increase with a semisynthetic diet containing tocopherol, but a decrease during alimentary lack of tocopherol and tocopherolquinone. The amount of secretory granules in the C-cells as seen with the electron microscope corresponds with the in vitro-activity of extracted calcitonin. The relations between the functional system of the thyrocytes and that of the C-cells are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307233
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  • 110
    Digitale Medien
    Digitale Medien
    The ultrastructure of the A1 sensilla on the posterior surface of the clypeo-labrum of Locusta migratoria migratorioides (R and F) (1972)
    Springer
    Cell & tissue research 134 (1972), S. 539-554 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Chemoreceptors ; Locusta ; Clypeo-labrum ; Light and electron microscopy ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The A1 sensilla are asymmetric in distribution. Each sensillum contains five bipolar neurons, the distal regions of which extend to the tip of a cuticular cone which has a terminal pore. This was shown with the scanning electron microscope, but was not seen in section. The receptor-lymph cavity of the tormogen cell and the basal cavity of the neurilemma cell contain an electron-dense material unlike other contact chemoreceptors of Locusta prepared for electron microscopy in the same manner. Isolated axons of unknown function occur below the basement membrane and also between epidermal cells surrounding the sensillum.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307673
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  • 111
    Digitale Medien
    Digitale Medien
    Ultrastructure of the anuran pars intermedia following severance of hypothalamic connection (1972)
    Springer
    Cell & tissue research 131 (1972), S. 545-557 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pars intermedia ; Hypothalamus ; Anurans ; Hormone release ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of the pars intermedia of Rana catesbeiana tadpoles was studied following isolation from the hypothalamus, in vivo after sectioning of the pituitary stalk, and in vitro after implantation of the pituitary into a piece of tail fin. Both experimental procedures were followed by rapid and sustained skin darkening. Pituitaries from normal light and dark adapted tadpoles served as controls. In 4-hour disinhibited glands, melanotrophs revealed hyperactive Golgi bodies, colloid vesicles (1–2 microns) in close proximity to axon terminals, and no apparent loss of secretory granules. At 24 hours extracellular colloid adjacent to axon terminals was found, and extensive arrays of RER appeared in the melanotrophs. Obvious granule loss from secretory cells occurred within a week, by which time the cytoplasm was occupied by large cisterns of SER and RER and abundant free ribosomes. Dense core vesicles (600–900 Å) in aminergic nerve terminals disappeared shortly after isolation of the pituitary from the hypothalamus, and only decreasing numbers of translucent vesicles (200–300 Å) were found. The functional significance of these changes is discussed, with particular emphasis on the mode of acute hormone release.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00306970
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  • 112
    Digitale Medien
    Digitale Medien
    Oligodendrocytes in the normal and chronically de-afferented lateral geniculate body of the monkey (1972)
    Springer
    Cell & tissue research 135 (1972), S. 115-127 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Oligodendroglia ; Monkey ; De-afferentation ; Ultrastructure ; Densebodies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Electron microscopical examination of the norma and de-afferented ‘laterall geniculate body’ of the monkey following paraformaldehyde-glutaraldehyde vascular perfusion revealed distinctive morphological features of different types of oligodendrocyte. These cells were normally situated as perineuronal satellites or in relation to axons and capillaries. A wide range of nuclear and cytoplasmic densities were displayed by both satellite and interfascicular oligodendrocytes. The following distinctive features for the identification of ligodendrocytes were utilised: the presence of large quantities of free ribosomes and ribosomal rosettes, microtubular profiles, dense marginal aggregation of nuclear chromatin together with light patches and numerous nuclear pores; but the absence of broad cytoplasmic processes, glycogen and gliofibrils. Circumferential perinuclear organization of the cytoplasmic organelles was typical of oligodendrocytes. Particular attention was paid to perineuronal satellite cells in view of the known transneuronal atrophy in the de-afferented geniculate body. Some cells having a nuclear pattern of oligodendrocytes but showing hyalinisation of perikaryon were seen in de-afferented laminae. A notable feature was the presence of variegated “osmiophilic bodies” in the perikaryon of oligodendrocytes also situated in the de-afferented laminae. A cell type combining the features of oligodendrocytes and astrocytes was classified as ‘intermediate neuroglia’.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307092
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  • 113
    Digitale Medien
    Digitale Medien
    Les cellules corticotropes de l'hypophyse d'un Amphibien après interrénalectomie (1972)
    Springer
    Cell & tissue research 132 (1972), S. 333-364 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pituitary gland ; Amphibians ; Corticotrophs ; Ultrastructure ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé L'identification des cellules responsables de l'élaboration de la corticotropine (ACTH) a été envisagée chezRana esculenta. Les effects causés par l'interrénalectomie au niveau de l'hypophyse ont été étudiés parallèlement par immunofluorescence et au microscope électronique. Au microscope à fluorescence, les cellules détectées chez les animaux témoins avec un antisérum anti-synachten1 bordent en grand nombre les capillaires des zones médiorostrale et ventrale du lobe antérieur. Deux jours après interrénalectomie, le nombre de cellules fluorescentes décroît, douze jours après l'intervention, il ne subsiste pas d'éléments fluorescents dans cette zone. Au microscope électronique, les cellules corticotropes présentent de fines granulations d'environ 200 mμ de diamètre. Après interrénalectomie bilatérale, ces cellules sont fortement stimulées, elles sont sujettes à d'importantes modifications morphologiques; l'aspect morphologique des autres catégories de cellules antéhypophysaires, par contre, n'est pratiquement pas modifié. Douze jours après l'opération, la plupart de ces cellules sont dégranulées, l'ergastoplasme et l'appareil de Golgi sont bien développés. Ces observations suggèrent que les cellules péricapillaires de la moitié rostrale de lapars distalis sécrètent l'hormone corticotrope.
    Notizen: Summary Identification of the cell types responsible for the production of adrenocorticotropin (ACTH) was performed inRana esculenta. The effects of interrenalectomy on the pituitary cells were studied as well by immunofluorescence, as by electron microscopy. In control animals, the ACTH cells studied by immunofluorescence are numerous around the blood vessels of the medio-rostral and medio-ventral part of the anterior lobe. Two days after interrenalectomy the number of fluorescent cells decreases. Twelve days after, the operation all the fluorescent cells disappeared. The fine structure of the corticotrophs is characterized by the presence of small secretory granules (200 mμ). After bilateral interrenalectomy this cell type is markedly stimulated; it displays striking morphological changes, while the morphology of the other pituitary cell types is not considerably modified. Twelve days after operation most of these cells are degranulated, the rough endoplasmic reticulum and the Golgi apparatus are well developed. These findings suggest that the pericapillary cells of the rostral half of thepars distalis produce the adrenocorticotrophic hormone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02450713
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  • 114
    Digitale Medien
    Digitale Medien
    Ultrastruktur des Pseudoculus vonEosentomon (Protura, Insecta) (1972)
    Springer
    Cell & tissue research 135 (1972), S. 539-551 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pseudoculus ; Eosentomon (Protura, Insecta) ; Sense organ ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung In der Feinstruktur unterscheidet sich der Pseudoculus vonEosentomon nicht wesentlich von dem der Acerentomiden. Durch einen Endokutikulaporus treten die dendritischen Fortsätze zweier Sinneszellen, jeweils umgeben von einer Hüllzelle, in den Außenraum des Pseudoculus ein. Der Außenraum wird nach distal von einer äußeren Kutikulaschicht — vermutlich Epikutikula — abgeschlossen. Sie vermittelt durch regelmäßig angeordnete lange Spalten die Verbindung zur Außenwelt. Am Grunde der Spalten finden sich Porentubuli, die mit den Hüllzellen oder den distalen Fortsätzen der Dendriten Kontakt haben können. Aus der Feinstruktur kann geschlossen werden, daß der Pseudoculus als Chemo-, Hygro- und/oder Thermorezeptor fungiert.
    Notizen: Summary Concerning its fine structure the pseudoculus of Eosentomon is quite similar to that of Acerentomide Protura. There are two sensory cells innervating the organ. From each of them one dendritic process derives, surrounded by one enveloping cell. The processes of these four cells enter the distal cavity of the pseudoculus through a pore in the endocuticular layer. The cuticular layer of the cap seems to consist of epicuticle only. It is furrowed by long clefts connecting the distal cavity of the organ with the outside. Poretubules insert at the base of the clefts and may have contact with the cell membranes of both enveloping cells and dendritic processes. According to its structure the pseudoculus may function as chemo-, hygro- and/or thermoreceptor.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00583435
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  • 115
    Digitale Medien
    Digitale Medien
    Nervous system of the snailHelix aspersa (1972)
    Springer
    Cell & tissue research 135 (1972), S. 473-482 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Neurosecretory nerves ; Glial and pigment cells ; Neural sheath ; Gastropods ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fine structure of neurosecretory nerves and endings associated with the sheath of the infraesophageal ganglion ofHelix aspersa is described. The sheath is a neurohemal organ whose vascularized stroma receives both monoaminergic and peptidergic endings. The latter occur along the surface of the nerves or scattered within the stroma. They include a complex population of vesicular profiles. The granular vesicles (1300–3000 Å in diameter) exhibit structural modifications that may be related to the intra-axonal release of their neurohormones. The agranular vesicles (500–2000 Å in diameter) occur in large numbers and lie mostly adjacent to the axon surface. Synaptoid specializations seem to represent active sites for the extracellular discharge of neurosecretory material. The monoaminergic endings so far studied lack synaptoid specializations and contain small granular (800–1300 Å in diameter) and agranular (700 Å in diameter) vesicles. Two kinds of non-neural cells are associated with the nerves: glial cells and melanocytes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00583431
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  • 116
    Digitale Medien
    Digitale Medien
    Spatial configurations of polynucleotide chains. I. Steric interactions in polyribonucleotides: A virtual bond modelFrom the thesis submitted by Wilma K. Olson in fulfillment of the requirements for the degree of Doctor of Philosophy, Stanford University, 1971. (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1-23 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A simplified scheme for treating the spatial configurations of polynucleotide chains is developed using the rotational isomeric state approximation and statistical methods applicable to linear systems of interacting subunits. As a consequence of geometric constraints imposed by the skeletal structure and of the severity of certain steric interactions, it is possible to represent the repeat unit comprising six skeletal bonds by two virtual bonds of fixed length. The configuration of the polynucleotide chain as a whole may be conveniently described by an alternating succession of these two virtual bonds. Moreover, analysis of steric interactions suggests that bond rotations governing the mutual orientation of a given pair of successive virtual bonds should be sensibly independent of the rotations affecting the mutual orientation of other pairs. The statistical mechanical treatment of configuration-dependent properties is much simplified in consequence of this mutual independence. Mean-square dimensions calculated by giving equal weights to all sterically allowed conformations are much smaller than values determined by Felsenfeld and co-workers. The calculated dimensions are markedly increased, however, by placing certain arbitrary restrictions on the rotations about selected pairs of skeletal bonds. It is thus demonstrated that steric interactions alone are insufficient to account for the spatial characteristics of polynucleotide chains. The dimensions are also found to be sensitive to the conformation of the ribose ring of each nucleotide unit, but, insofar as the influences of steric interactions are concerned, the dimensions do not depend on the heterocyclic base attached to the ribose ring.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110102
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  • 117
    Digitale Medien
    Digitale Medien
    Isoenzymes of tetrameric proteins (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 119-126 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A theory is presented concerning the possible arrangements of protomers in tetrameric molecules. Isoenzymes may exist even in the case of homotetramers if the asymmetry of the identical protomers is detectable. The number of tetrahedral isoenzymes that can be isolated depends on the nature of the intersubunit bonds and on the level of the asymmetry of the protomers. Five isoenzymes can be distinguished only if two different types of protomers form tetrahedral tetramers and the asymmetry of protomers is not detectable with the method used. If the two types of protomers can bind each other by any pairs of binding sets and the asymmetry of both protomer types reaches the level of detection with the method used, we obtain 117 isoenzymes: 15 individual ones, and 51 stereoisomeric pairs.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110109
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  • 118
    Digitale Medien
    Digitale Medien
    Graphical approach to non-ideal cases of self-associating protein systems (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 197-214 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Our previous paper described graphical procedures for evaluating the mode of association in ideal discrete and indefinite cases. This paper concerns the application of such procedures in cases where the non-ideality term BM1 must be considered. Bovine liver L-glutamate dehydrogenase and lysozyme are used as model systems. Several graphical procedures for dealing with cases of 1 - m, 1 - m - n, or indefinite association are developed. The procedure is based on the evaluation of the weight-fraction monomer with-out prior calculation of BM1, using graphical analysis to evaluate the non-ideality term.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110115
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  • 119
    Digitale Medien
    Digitale Medien
    Fibrillar aggregates of poly-γ-benzyl-L-glutamate (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 271-278 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110120
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  • 120
    Digitale Medien
    Digitale Medien
    Lysine oligopeptides. Preparation by ion-exchange chromatographyOn leave from the Department of Biophysics, The Weizmann Institute of Science, Rehovot, Israel. (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 607-621 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The preparation of L-lysine peptides (Lysn, n = 2-14) from polyL-lysine is described. Fractionation by ion-exchange column chromatography of poly-L-lysine hydrolysates on a preparative scale resulted in 0.2-1.0 g quantities of individual members of the poly-L-lysine series. The peptides isolated proved to be analytically pure and the optical configuration was fully retained, as demonstrated by complete enzymic digestion. Peptides higher than n = 14 were also prepared. They consisted of oligolysine groups of narrow and accurately determined size distribution. Potentiometric titrations were used both to characterize the products and to demonstrate the characteristic dependence of the dissociation constants on size of the peptide.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110306
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  • 121
    Digitale Medien
    Digitale Medien
    Independence of length and temperature effects on the rate of helix formation between complementary ribopolymers (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 549-561 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate of double helix formation by single stranded Poly A plus Poly U, Poly I plus Poly C, Poly G plus Poly C, and T2 DNA has been investigated as a function of both the length of the reacting strands and temperature. The length dependence of the rate is found to be independent of temperature. All of the reactions studied show a rate approximately proportional to the square root of the length of the shorter of the complementary strands. At or about 30°C below the melting temperature the ribopolymers react with about the same rate. This rate is four to five times slower than DNA renaturation rates. The effect of temperature on ribopolymer reaction rates is interpreted in terms of a steady-state model for helix propagation.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110303
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  • 122
    Digitale Medien
    Digitale Medien
    Evidence for stereospecific collision complexes of cyclo(tri-L-prolyl) with benzene (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 653-659 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: NMR spectra of cyclo(tri-L-prolyl), c-(P)3, show large shifts of the Hα resonance on adding C6D6 to a solution of c-(P)3 in CD2Cl2. CPK models and observed coupling constants indicate a rigid c-(P)3 conformation, independent of solvent composition, suggesting that these shifts result from formation of stereospecific C6D6-c-(P)3 collision complexes in which the c-(P)3 Hα lie near the face of the aromatic ring. The temperature dependence of the Hα shifts and the solvent dependent shifts observed on adding toluene-d8 or nitrobenzene-d5 to the c-(P)3 solution suggest that preferred C6D6-c-(P)3 orientations result from attractive interactions between the electron-rich aromatic ring and the electropositive Hα's and/or δ+ nitrogen atoms in the peptide backbone. Reports of such interactions in increasingly diverse peptide model systems suggest that they may play a role in stabilizing protein structures.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110310
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  • 123
    Digitale Medien
    Digitale Medien
    Thermal denaturation of nucleohistones - effects of formaldehyde reaction (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 835-847 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Thermal denaturation of native or partially dehistonized nucleohistones shows two melting bands at 66 and 81° in 2.5 × 10-4 M EDTA, pH 8.0. These correspond to the melting of DNA segments bound by the less basic and the more basic half-molecules of histones, respectively. These two melting bands combine into a broad melting band from around 70 to 85° when these nucleohistones are pre-treated with formaldehyde. A formaldehyde reaction which fixes histones on DNA by covalent bonds account for the effect. Formaldehyde fixation also increases the melting temperature of some free DNA segments from around 42 to around 55°. This is interpreted as a result of closed or rigid boundaries between free DNA and formaldehyde-reacted histone-bound DNA segments. MgCl2 dissociates histones from DNA more effectively and leaves longer free DNA segments than does NaCl. Thermal denaturation of a formaldehyde-reacted nucleoprotein thus provides an effective tool for comparing the relative size of free DNA regions on nucleoproteins. The effect of reversible binding of ligands on helix-coil transition of DNA is descussed and found not adequate for thermal denaturation of nucleohistones.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110408
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  • 124
    Digitale Medien
    Digitale Medien
    Linear relaxation analysis of the mechanochemical transformation of collagen fibers (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 899-912 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The isometric tensile stress generation observed when collagen fibers are immersed in aqueous solutions of lithium bromide ranging in molar concentration up to 7 was studied at 23°C. The reverse process, namely, isometric stress relaxation of the fiber occurring by subsequent immersion in distilled water, was also studied. We find that the data in the region of LiBr concentration up to about 2.5 moles/liter are adequately represented by a superposition integral \documentclass{article}\pagestyle{empty}\begin{document}$$ \sigma (t) = \int_{ - \infty }^\infty {K(t - \tau )} \frac{{dc(\tau )}}{{d\tau }}\,d\tau $$\end{document} where σ(t) is the time-dependent stress generated by the collagen fiber held at fixed length, c(t) is the history of LiBr molar concentration, and K(t) is the isometric contractility function, expressed as stress per unit salt concentration. We conclude that, within a limited range of salt concentration, a collagen fiber in a LiBr bath behaves as if it were a linear, time-invariant system defined mechanochemically by a single function K(t) which depends on the structural characteristics of the fiber while being independent of salt concentration. An analysis is presented of isometric mechanochemical data obtained under conditions of equilibrium by other workers who studied the behavior of collagen fibers in aqueous solutions either of urea, LiBr, or KCNS. The analysis shows that these independent (equilibrium) data confirm the linarity of the relation between isometric contractile stress and salt concentration on which our superposition integral representation is based. We also find that the asymptotic (infinite-time) value of the isometric stress is linearly related to the chemical potential of the salt as well, in agreement with the equilibrium thermodynamic treatment of mechanochemical processes by Katchalsky and Oplatka.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110413
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  • 125
    Digitale Medien
    Digitale Medien
    Thermodynamic analysis of thermal transitions in globular proteins. I. Calorimetric study of ribotrypsinogen, ribonuclease, and myoglobin (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 935-935 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110415
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  • 126
    Digitale Medien
    Digitale Medien
    On the application of polyelectrolyte “limiting laws” to the helix-coil transition of DNA. I. Excess univalent cations (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 937-949 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A general theory of polyelectrolyte solutions is here used to calculate the differences in Gibbs free energy, enthalpy, and entropy between the coil and helix forms of DNA at any temperature and salt concentration. The salt has univalent cations and is assumed present in excess over the base concentration. The results are restricted to sufficiently dilute solutions. It is shown that the salt concentrations effect is entirely entropic in origin. When applied to the melting temperature, the calculations yield a relation between the enthalpy difference at the melting temperature and the slope of the plot of melting temperature vs. the logarithm of the salt concentration. In accord with observation, both the Gibbs free energy difference at any fixed temperature and the melting temperature are predicted to be linear functions of the log of the salt concentration.However, the theory is not in quantitative agreement with enthalpy data. Data on various colligative and transport properties of both helix and coil forms are reviewed in the text and in Appendix B, and good agreement is found with theory for both forms. No attempt is made to explain why the theory is quantitative for these properties but not for heat measurements.Finally, in Appendix A, an approximate calculation is made of the free energy contributions due to ionic effects not associated with the salt concentration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110502
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  • 127
    Digitale Medien
    Digitale Medien
    The conformation fo poly-L-alanine in hexafluoroisopropanol (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1001-1020 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: High-molecular-weight poly-L-alanine dissolved in hexafluoroisopropanol exhibits infrared, ultraviolet, circular dichroism, and optical rotatory dispersion spectra which are unique and unlike any other previously reported polypeptide spectra. Strong evidence that a helical conformation is present is shown by the high degree of hypochromism in the 187mμ absorption peak and by the positions of the amide infrared bands. The CD and ORD spectra are also similar to those of α-helical polypeptides, though important qualitative and qualitative differences are observed. To explain the novel spectra, which are not mixtures of the spectra of previously reported polypeptide conformations, a new α-helix-like conformation is proposed. The postulated conformation (a doubly hydrogen-bonded helix) is a distorted α-helix in which the peptide carbonyl groups point slightly out from the helix axis and are hydrogen bonded simul taneously both to the NH of the fourth peptide residue to the carboxyl terminal side (as in the classical α-helix), as well as to a solvent molecule's hydroxyl hydrogen.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110506
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  • 128
    Digitale Medien
    Digitale Medien
    PPP calculations of the circular dichroism spectra of some dinucleoside phosphates (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1091-1102 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Circular dichriosm (CD) spectra have been calculated for serveral dinucleoside phosphates using a variant of the Pariser-Parr-Pople π-electron molecular orbital method. This method does not require the prior knowledge of the experimental absorption spectra of transition moments of the bases forming the dinucleoside phosphates. Calculated spectra were obtained in good agreement with experimental spectra for four dinucleoside phosphates, ApA, UpU, GpA, and UpA, and reasonable agreement was obtained for ApG and ApU. The effect of changing conformation on the CD spectrum was studied for ApA, UpU, UpA, and ApU; the spectra of UpU, UpA, and ApU were sensitive to small change in conformation, whereas ApA was insensitive over the range of conformation studied. Further studies await detailed knowledge of the structure of dinucleoside phosphates in solution.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110511
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  • 129
    Digitale Medien
    Digitale Medien
    Synthesis and conformational study of poly(N∊-benzyl-L-lysine) and its benzyloxycarbonyl derivative (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1259-1268 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The solvent-and pH-induced conformational changes are examined in order to investigate the influence of benzyl group. Polymer was prepared via N∊-benzyloxycarbonyl, N∊-benzyl-Nα-carboxy-L-lysine anhydride. The resulting poly (N∊-benzyloxycarbonyl, N∊-benzyl-L-lysine) was obtained in high yield and had a high molecular weight. The protected polymer was removed into poly (N∊-benzyl-L-lysine) by treating it with hydrogen bromide. From the results of the ORD and CD, the protected polymer has a righthanded α-helix, showing [m′]233 = -10,300, [θ]220 = -27,600 and [θ]207 = -25,100 in dioxane. The breakdown of the helical conformation is found to occur at 8% dichloroacetic acid in chloroform-dichloroacetic acid mixture. In the pH range 3.35-6.90, poly (N∊-benzyl-L-lysine) is in a random coil structure. In the pH range 7.50-13.0, the polypeptide has a right-handed α-helix structure; [m′]233 = -12,000, [0]220 = -27,200, and [0]207 = -27,000. In comparison with poly-L-lysine, the coil-to-helix transition is observed at lower pH range in 50% n-propanol. Above pH 8 by heating, the α ⇀ β transition of poly (N∊-benzyl-L-lysine) is not observed in an aqueous media.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110610
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  • 130
    Digitale Medien
    Digitale Medien
    Detection of polar side-chain hydration in polypeptides by near-infrared spectroscopy (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1305-1310 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110614
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  • 131
    Digitale Medien
    Digitale Medien
    Simple sequential model for the kinetics of conformational transitions of oligomeric helices and proteins (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1499-1520 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A simple sequential model is developed which is applicable to the kinetics of melting of some types of oligomeric helices and as an idealization to the kinetics of unfolding of some protein molecules. A procedure is presented for calculating the concentrations of all conformational species as functions of time. The time course of experimentally observable quantities which depend on these concentrations may then be computed.One of the most characteristic features of the model is the distinction between a transient and a steady-state phase. During the latter all molecular parameters change at the same rate, which depends strongly on the difficulty of nucleation and the length of the sequence. Simple approximations to the steady-state rate are discussed in terms of the exact solution. Rates of transient processes dependless strongly on the rate of nucleation and the number of steps and are a more direct reflection of the rates of the rates of the elementary process of propagation. The value of experimental observation of transient process is emphasized.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110713
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  • 132
    Digitale Medien
    Digitale Medien
    Masthead (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972) 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110801
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  • 133
    Digitale Medien
    Digitale Medien
    Far-infrared spectra of sequential copolymers of amino acids with alkyl group side chains (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1593-1605 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Far-infrared spectra were measured for the sequential copolymers of amino acids with alkyl group side chains. The analysis of the spectra showed that (L-Ala-L-Ala-Gly)n, (L-Ala-Gly)n, (L-Ala-Gly-Gly)n, (L-Val-L-Ala-L-Ala)n, and (L-Val-L-Ala)n, have the antiparallel pleated sheet structures and that the backbone conformations of (L-Val-L-Val-L-Ala)n and (L-Val-L-Val-Gly)n are the same as that of poly-L-valine. The far-infrared bands characteristic of the antiparallel pleated sheet structure were assigned on the basis of the result of the normal coordinate analysis of poly-L-alanine with this structure. The intersheet and interchain spacings of the sequential copolymers with the antiparallel pleated sheet structure were determined from the x-ray powder-diffraction patterns of these samples.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110806
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  • 134
    Digitale Medien
    Digitale Medien
    Induced cotton effects of tRNA-acridine orange complex and tRNA conformation (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1583-1592 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Circular dichroism spectra of acridine orange bound to E. coli tRNA were studied at varying tRNA phosphate-to-dye (P/D) ratios for both unfractionated and purified materials in the absence of Mg++. From the rather discrete features exhibited in the circular dichroism spectra three types of interactions were observed: (1) A high P/D ratio such as 75.2 or 49.8 indicates the interaction between the nucleotide base and dye molecule. The spectra with a large positive peak at 515 mμ are, however, quite different from that of DNA-AO complex under similar conditions. (2) With an intermediate P/D ratio (26.5 to 9.6) dye molecules bound strongly to the polynucleotide chain. (3) With low P/D ratios (≤7.5) the interaction appears to be due to the stacked dye molecules in the single-stranded part of tRNA. The spectra of the third group have an isobestic point at 477 mμ. Below a P/D ratio of 4 the spectrum shows one positive and two negative bands which may be the characteristics of circular dichroism of stacked dyes in polynucleotide chain.Although no drastic change in the conformation of tRNA itself was detectable in the presence of Mg++ in the ultraviolet region, a dramatic change was observed in the circular dichroism of tRNA-acridine orange complex when Mg++ concentration was increased to 10-3M. It was inferred that certain conformational changes other than simple hydrogen bond formation occured in tRNA molecules at this high Mg++ concentration, so that the amount of bound dye in the stacking condition was increased through the transition.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110805
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  • 135
    Digitale Medien
    Digitale Medien
    The hydrolysis of poly (L-prolyl-glycyl-L-prolyl) by bacterial collagenase (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1607-1612 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Poly (L-Prolyl-Glycyl-L-Prolyl), a polymer which resembles collagen by physical and immunochemical criteria, has been shown to serve as a substrate for the highly specific bacterial collagenase obtained from Clostridium histolyticum. The postulated reaction products Gly Pro, Gly Pro Pro, and Pro Gly Pro Pro have been isolated. The enzyme has been employed as an analytical tool in elucidating the sequence of synthesized polymers of proline and glycine.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110807
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  • 136
    Digitale Medien
    Digitale Medien
    Effect of non-complementary nucleotides on the rate of helix formation: Kinetics of formation of poly (I)·poly (C,I) and poly (I)·poly (C,U) complexes (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1613-1620 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Apparent second-order rate constants for complex formation between poly (I) and poly (C) and copolymers of C containing non-complementary I or U residues have been determined spectrophotometrically. The rate constants decrease as the concentration of either I or U in the C strands increases-the effect seems insensitive to the species of residue involved, when differences in the thermal stabilities of the poly (I) poly (C,I) and poly (I). poly (C,U) complexes are taken into account. These results suggest that low concentrations of relatively stable defects can alter the apparent kinetic “complexity” of polynucleotides as determined by hybridization methods (C0t analysis).
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110808
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  • 137
    Digitale Medien
    Digitale Medien
    The kinetics of the renaturation of deoxyribonucleic acid denatured in the presence of copper (II) ions (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1661-1684 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: DNA which has been heat denatured in the presence of Cu++ ions can be completely and rapidly renatured by increasing the ionic strength of the solution above a critical value. A kinetic study of this renaturation recation was carried out by following the associated UV absorbance change and also by following the change in free Cu++ ion concentration by means of a specific Cu++ ion activity electrode. The data obtained could be fitted to first-order kinetics for a considerable extent of the reaction and the rate constant was found to increase with temperature and ionic strength, but to decrease markedly as the bulk viscosity of the solution was increased. At temperatures greater than 5°C the reaction rate depended on the time elapsing between denaturation and the commencement of the renaturation reaction. As there was good agreement between the rate constants obtained by following the decrease in hyperchromism and by following the increase in free Cu++ ion concentration, it is concluded that under the conditions employed, the rate of renaturation is determined by the rate of release of Cu++ ions from the denatured DNA-Cu++ complex.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110812
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  • 138
    Digitale Medien
    Digitale Medien
    Conformational studies on copolymers of L-leusine and L-leucine: Circular dichroism and potentiometric titration studies (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1723-1744 
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    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Conformational aspects of a series of copolymers of L-Leucine and L-leucine [poly-(LysxLeuy)] containing 0 to 0.41 mole fraction L-leucine have been studied by circular dichroism (CD) and potentiometric titration in 0.05M KF solution. CD studies on the α-helical conformation showed a dependence of the magnitude of the CD ellipticity band at 222 nm on copolymer composition; the [θ]222 decreasing with higher leucine contents. This was interpreted as the result of an increase of the hydrophobicity of the environment of the amide group due to the presence of the leucyl residues. Values of the Zimm-Rice parameter, σ, for the copolymers were obtained from the potentiometric titrations and used to fit theoretical curves to the experimental data. Using the variation of σ with polymer composition, a value of σ for the leucyl residue was estimated to be 6.3 × 10-2, assuming independence of σ on the amino acid sequence in the copolymer. The free energy change for the conversion of one mole residue from uncharged helix to uncharged coil, ΔGhc°, was also obtained from the titration data for each copolymer up to a leucine mole fraction of 0.16; a value of 385 cal mole-1 was estimated for ΔGhc° for a leucyl residue. These values for σ and ΔGhc° are compared with other values in the literature for various amino acid residues obtained from titration and melting curve data.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110817
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  • 139
    Digitale Medien
    Digitale Medien
    The absence of an isotope effect on the stability of the poly-β-benzyl-L-aspartate α-helix in aprotic solvents (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1745-1763 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Optical rotatory dispersion measurements were used to follow the transition from the helical to the random coil conformation of poly-β-benzyl-L-aspartate as induced by changes in temperature and solvent composition in mixtures of dioxane and dimethylsulfoxide. Within experimental error, there is no difference in the stability of the helical state as measured in this way for the protonated and deuterated forms of the polypeptide. This result is considered in terms of previous attempts to study the isotope effect on conformational transitions of helical biological macromolecules and polypeptides. The conclusion is drawn that the apparent changes in conformational stability observed in these previous systems arise from alteration of the properties of the solvent. Speculations are advanced regarding the contribution of the interpeptide bond to the stability of the helical state.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110818
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  • 140
    Digitale Medien
    Digitale Medien
    Conformational aspects of polypeptide structure. XLI. Crystal structure of S-thiazolidine-4-carboxylic acid and helical structure of poly[(S)-thiazolidine-4-carboxylic acid]This work was carried out at the Polytechnic Institute of Brooklyn and the Istituto Chimico, Naples, Italy. (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1779-1787 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The helical structures of poly[(S)-thiazolidine-4-carboxylic acid], in the cis and trans forms, were redetermined by using the new sets of bond angles and bond lengths established by X-ray diffraction analysis of L-thioproline. Calculations of the helical structures of poly-L-proline and poly[(S)-oxazolidine-4-carboxylic acid] were also repeated. As a result of these energy calculations, it is suggested that, in contrast to poly-L-proline and poly[(S)-oxazolidine-4-carboxylic acid], poly[(S)-thiazolidine-4-carboxylic acid] should not mutarotate from the trans to the cis form. This result is due to the fact that the energy barrier for the conversion is most likely too high. Previous experimental work is consistent with this finding.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110903
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  • 141
    Digitale Medien
    Digitale Medien
    Optical rotatory dispersion and circular dichroism of benzoyl polysaccharidesParts of this work were presented at the “Makromolekulare Kolloquium” 1969, Freiburg/Brsg., BRD. (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1997-2013 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Measurements of optical rotatory dispersion (ORD) and circular dichroism (CD) were made in the range of 400-205 nm for polysaccharide tribenzoates such as 2,3,6-tri-O-benzoyl amylose (I), 2,3,4-tri-O-benzoyl dextran (II), tri-O-benzoyl pullulan (III), 2,3,6-tri-O-benzoyl cellulose (IV), 2,3,6-tri-O-benzoyl mannan (V), and polyglycan dibenzoates such as 2,3,-di-O-benzoyl amylose (VI), cellulose (VII), and mannan (VIII). All compounds exhibit Cotton effects in the region of their UV absorption bands (206-285 nm).Comparison of the corresponding di- and tribenzoyl polysaccharides shows a qualitative agreement in number, position and sign of the CD bands but differences in ellipticity magnitude. The disubstituted derivatives exhibit smaller amplitudes than the trisubstituted ones. The contribution of the C(6) chromophore (linked by a CH2-group to the asymmetric C(5) atom) was determined to be of the same sign as the combined contribution of the C(2) and C(3) substituents.The CD bonds of the individual polysaccharide derivatives, which differ in number, sign, and position, were discussed in terms of the steric position of the single chromophores and the steric arrangement and interaction caused by the configuration of the polysaccharides. The optical behavior of these polysaccharide derivatives was found to be not strongly influenced by a definite chain conformation in solution.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111002
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  • 142
    Digitale Medien
    Digitale Medien
    Spectroscopic study of monosubstituted amides. II. Rotation isomers in amides substituted by aliphatic side-chain modelsFor Part I See Ref. 3. This paper is one part of F. Fillaux's thesis registered by the CNRS (France) under No. A07245. (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2063-2077 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The influence of the substituents upon the Amide I and νNH frequencies has been analyzed for ten amides substituted by aliphatic side chains. By considering the aliphatic chain field effect, some data are obtained as to the conformation of the N—Cα bond. In two amides, the presence of an equilibrium between two conformers is shown and a semiquantitative estimation of the energies involved is obtained. The consequences for polypeptides conformation, especially for poly-L-valine, are discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111007
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  • 143
    Digitale Medien
    Digitale Medien
    Viscosity of heparin as a function of dielectric constant and of desulfation (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2079-2090 
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    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The effect of dielectric constant (D) of the solvent on the viscosity of heparin was examined using the relation \documentclass{article}\pagestyle{empty}\begin{document}$ \eta _{{\rm sp}} /c = [\eta ]_\infty (1 + k/\sqrt c) $\end{document}, where [η]∞ is the shielded intrinsic viscosity obtained by extrapolating \documentclass{article}\pagestyle{empty}\begin{document}$ \eta _{{\rm sp}} /c\,{\rm vs}{\rm . }\,1/\sqrt c ) $\end{document} to infinite concentration, and k is an interaction parameter independent of the dielectric constant of the solvent. This equation was previously reported by the authors9 for describing the reduced viscosities of strong polyelectrolytes in salt-free polar solvents. It was found that the [η]∞ of heparin increases linearly with increasing dielectric constant of the solvent whereas the k values were, within experimental error, independent of D in the range 54.7 〈 D 〈 93.2 examined. Graded hydrolysis of heparin from its acid form (heparinic acid) at 57°C resulted in samples of varying degree of desulfation with corresponding decrease in biological activity. It was found that both [η]∞ and k decrease with increasing desulfation.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111008
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  • 144
    Digitale Medien
    Digitale Medien
    New banding species, with densities of phage-ghost clusters, produced from lambda phage particles on storage (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2171-2177 
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    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Density gradient analysis of purified lambda phage particles after storage reveals that minor species with new banding desities arise during storage. These have densities expected for phage-ghost clusters containing integra rations of ghosts to phage particles. A lage numbersof new banding species has been observed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111016
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  • 145
    Digitale Medien
    Digitale Medien
    Synthetic peptides related to the entire sequence of yeast iso-1-cytochrome C (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2191-2194 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111019
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  • 146
    Digitale Medien
    Digitale Medien
    A comparative X-ray study of a nucleoprotamine and DNA complexes with polylysine and polyarginine (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2223-2231 
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    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The high-humidity X-ray pattern of oriented fibers prepared from salmon spermheads strongly resembles that of DNA in the B form. However, the nucleoprotamine pattern has a more intense first layer line and increased lateral unit-cell dimensions.Complexes of DNA with poly-L-lysine and poly-L-arginine were prepared and photographed at various relative humidities. The most crystalline patterns were obtained at 92% and also indicate DNA in the B form. However, whereas polylysine-DNA, like the spermheads, has a primitive hexagonal cell, polyarginine-DNA, like NaDNA, has three molecules in the unit cell. Polylysine-DNA, but not polyarginine-DNA, also resembles spermheads in having a strong first layer line.All three complexes show increasing intermolecular distance with increasing humidity, but with sharp maxima when photographed in water, which indicates cross-linking between the molecules. Lowering the humidity causes the polylysine-DNA, but not polyarginine-DNA, to change conformation from the B to the C form.The structural implications of these results are discussed in the light of model-building studies and a comparison of calculated and observed X-ray intensities.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111103
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  • 147
    Digitale Medien
    Digitale Medien
    The pH dependence of tyrosine cyanuration in proteins (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2233-2240 
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    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The pH, temperature, and reagent concentration dependences of the cyanuration of tyrosines within proteins are compared with those of the free amino acid. The results indicate that the mechanism of the cyanuration reaction is a nucleophilic aromatic substitution of the SN2 type, where the tyrosine oxygen acts as a nucleophile and the displacement takes places at a carbon atom which is part of the six-membered ring of the s-triazene. This reaction must compete with the hydrolysis of cyanuric fluoride in aqueous media. These competing reactions generate curves for the pH dependence of the reactivity of tyrosine with cyanuric fluoride whihc vary in a predictable manner with the extent of ionization of tyrosine and the concentration of cyanuric fluoride. In the case of proteins, the dependence of the degree of tyrosine reactivity on pH and temperature within the pH range of full reactivity of the free amino acid reflects constraints imposed by the microenvironment of these groups within the three-dimensional structure of the macromolecule.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111104
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  • 148
    Digitale Medien
    Digitale Medien
    Salt bonding in proteins. A model for the abnormal hydrogen ion titration and the strong anion binding of serum albumin (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2197-2221 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Serum albumin undergoes a conformational change at pH 4, known as the N-F transition. In the customary Linderstrøm-Lang treatment of hydrogen ion titration, the carboxyl groups in serum albumin either have an abnormally low pK, or are buried in charged form, and the Linderstrøm-Lang charging parameter ω decreases dramatically at the N-F isomerization. In the present paper partition functions are derived and distribution functions are calculated for a model permitting salt bonding between the positively and negatively charged sites on a macromolecule. The N-form has an abnormally high salt bonding constant whereas that of the F-form corresponds to that of small ions. The result obtained is consistent with a “normal” intrinsic pK of the carboxyl groups of serum albumin without burying of any charges and with an unchanged ω. The nature of the postulated salt bonding is discussed.Further, it is shown that the “abnormal salt bonding” of serum albumin can explain its unusual ability to bind anions. Theoretical binding curves are calculated and compared with literature data of the Cl- binding of serum albumin. The relation of the present model to other models of hydrogen ion and anion binding to proteins is discussed. Some additional consequences of the present model are pointed out; a transition in the alkaline range, analogous to the acid transition, seems probable. Literature data support the existence of such a transition but do not allow detailed calculations at present.A general, thermodynamic treatment of the interactions between small ligands and macromolecules is outlined. Important points are the choice of the statistical-me- chanical ensemble and considerations of the fluctuations about the mean bonding, if (i) there are not only a ligand-locus interaction but also interligand interactions (in par- ticular intdigand attraction), or (ii) there is a conformational change in themacromole- cule depending on the ligand binding. In these cases, the binding isotherms obtained from thermodynamically closed systems (canonical ensemble) may erroneously indicate a distribution about a single probability maximum, i.e., the statistical mean binding N̄, and fluctuations about this value. The description of a phase change in a bound phase or a change in the “internal” self-interactions of a macromolecule requires a bind- ing equation permitting distributions about two maxima, i.e., (i) N1* 〈 N̄ (“thin” phase) and N2* 〉 N̄ (“condensed” phase) or (ii) two macromolecular conformations P′, and P″, having occupancy numbers N̄, and N̄2, respectively. The N-F transition is an example illustrating the relation between the complete distribution functions and the two-state approximation.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111102
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  • 149
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    Digitale Medien
    The β-conformation and association of low-molecular-weight poly-γ-benzyl-L-glutamate in Solutions (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 493-507 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Three samples of poly-γ-benzyl-L-glutamate have been prepared from γ-benzyl-N-carboxy-L-glutamate anhydride with n-hexylamine initiation at anhydride-to-initiator molar ratios, [A]/[I], of 3, 4, and 8, and their conformation and association in ethylene dichloride and dioxane have been investigated by means of infrared spectra and vapor-pressure osmometry. Two conformations, σ-and β-forms, are present in those solvents, and the content of β-form increases with increasing A/I value and concentration. At infinite dilution molecular association is absent, but the number-average molecular weight increases with cocentration, markedly in ethylene dichloride and, to a lesser extent, in dioxane. The fraction of residues involved in associated molecules have been estimated as a function of concentration. Combination of the content of β-structure with the fraction of association leads to the following results. The A/I 3 and 4 polymers form intermolecularly hydrogen-bonded aggregates, in which hydrogen-bonded residues are in the β-structure. The A/I 8 polymer has the intramolecularly hydrogen-bonded β-structure at very low concentrations, but it also forms intermolecularly hydrogen-bonded aggregates at high concentrations.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110214
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  • 150
    Digitale Medien
    Digitale Medien
    Perspectives report: Melting of DNA. Its study and application as a research method (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 527-528 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110218
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  • 151
    Digitale Medien
    Digitale Medien
    Dielectric dispersion of the α-helix at the transition region to random coil (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 587-605 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Dielectric studies have been carried out for the helix-coil transition of poly-β-benzyl-L-aspartate with m-cresol as a solvent. The transition of the solute molecules has been sharply reflected as a characteristic change in the dielectric dispersion curves in changing temperature. Two polarizations, one having a low and the other a high critical frequency, have appeared. According to theoretical considerations of a model of a broken helix, the former is found to come from the orientation. of helical sequences and the latter from the chemical relaxation due to the helix-coil transition. It also seems likely that the unfolded chain may have a polarizability which could not be neglected at the high-temperature side of the transition.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110305
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  • 152
    Digitale Medien
    Digitale Medien
    Conformational studies on polypeptides. The effect of sodium perchlorate on the conformation of poly-L-lysine and of random copolymers of L-lysine and L-phenylalanine in aqueous solution (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 633-643 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Circular Dichroism measurements have been carried out on poly-L-lysine (PLL) and on random copolymers of lysine and phenylalanine at various pH values and in the presence of different amounts of NaClO4. The results indicate that either the homopolymer or the copolymers at pH conditions at which the side-chain amino groups are fully protonated, assume the right-handed α-helical conformation in the presence of NaClO4. The results are interpreted in terms of specific binding of ClO4- ions on charged side-chain amino groups.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110308
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  • 153
    Digitale Medien
    Digitale Medien
    Pressure dependence of the helix-coil transition temperature for polynucleic acid helices (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 667-678 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Thermal denaturation of DNA's and the corresponding helix-coil transformation of artificial polyribonucleic and polydeoxyribonucleic acids have been studied extensively both theoretically1-13 and experimentally. 14-30 Much less work has been carried out on the properties of these polynucleic acids at high pressure, and in particular, on the presure dependence of the helix-coil transition temperature.31-33 Light-scattering techniques have been used in this study to measure the pressure dependence of the helix-coil transition temperature of the two- and three-stranded helices of polyriboadenylic and polyribouridilic acids and of calf thymus DNA. From the slopes of the transition temperature vs. pressure curves and heats of transition obtained from the literature,20,34 the following volume changes from these helix-coil transitions have been obtained: (a) -0.96 cc/mole of nucleotide base pairs for the poly (A + U) transition, (b) +0.35 cc/mole of nucleotide base trios for the poly (A + 2U) transition, and (c) +2.7 cc/mole of nucleotide base pairs for the DNA transition. The relative magnitudes and signs of these volume changes which show that poly (A + U) is destabilized by increased pressure, whereas poly (A + 2U) and calf thymus DNA are stabilized by increased pressure, indicates that further development of the helix-coil transition theory for polynucleotides is needed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110312
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  • 154
    Digitale Medien
    Digitale Medien
    The molecular weight of a fast sedimenting MS2 RNA form (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 735-735 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110319
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  • 155
    Digitale Medien
    Digitale Medien
    The helix-coil transitions of poly (dA). Poly (dT) and poly (dA-dT). Poly (dA-dT) (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 745-759 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Helix-coil transition curves are calculated for poly (dA) poly(dT) and poly (dA-dT) poly (dA-dT) using the integral equation approach of Goel and Montroll.5 The transitions are described by the loop entropy model with the exponent of the loop entropy factor, k, remaining an arbitrary constant. The theoretical calculations are compared with experimental transition curves of the two polymers. Results indicate that the stacking energies for these two polymers differ by about 1 kcal/mole of base pairs. Also, a fit between theory and experiment was not possible for k 〉 1.70.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110403
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  • 156
    Digitale Medien
    Digitale Medien
    The ultraviolet circular dichroism of some natural DNAs and an analysis of the spectra for sequence information (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 853-879 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The circular dichroism spectra of many natural DNAs and double-stranded synthetic polynucleotides were obtained. The eight first-neighbor contributions to the CD spectra of a DNA have been extracted from these data. Therefore, the CD spectrum for any DNA with known first-neighbor frequencies may be easily calculated. For a natural DNA the CD spectrum may be approximated by assuming the first-neighbor frequencies have the most probable values consistent with the base composition. Under favorable conditions, the measured CD spectrum can be used to determine thirteen of the sixteen first-neighbor frequencies of a DNA to ± 0.02 mole percent. The TG, CA, and TA first-neighbor cannot be unambiguously resolved by our method. The accuracy of the first-neighbor frequency analysis depends on the number of different first-neighbors present in the DNA and the extent to which they differ from the most probable value.The extinction coefficient at 260 nm and the base composition can also be calculated from the CD spectrum.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110410
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  • 157
    Digitale Medien
    Digitale Medien
    Spatial configuration of polynucleotide chains. II. Conformational energies and the average dimensions of polyribonucleotidesFrom the thesis submitted by Wilma K. Olson in fulfillment of the requirements for the degree of Doctor of Philosophy, Stanford University, 1971. (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 25-56 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Conformational energies are calculated for pairs of successive bond rotations within an internal residue of a polyribonucleotide chain. Contributions to these energies include bond torsional strain, van der Waals repulsions, London attractions, electrostatic interactions, and inductive interactions between nonbonded atoms in the nucleotide repeat unit. The average dimensions of unperturbed random-coil polyribonucleotide chains are then evaluated on the basis of energies thus estimated, using for this purpose the previously developed virtual bond treatment. The characteristic ratio \documentclass{article}\pagestyle{empty}\begin{document}$ C_\infty = \mathop {{\rm lim}}\limits_{n \to \infty } (\langle r^2 \rangle_0/nl^2) $\end{document} of the mean-square end-to-end distance calculated for polyribonucleotide chains in which all pentose rings are fixed in a C3′-endo conformation is ≈9; for chains consisting exclusively of C2′-endo units it is ≈25. These values are considerably greater than those obtained by giving equal weight to all conformations judged to be sterically allowed. Satisfactory agreement between the calculations here and experimental values from viscosity and light-scattering studies is achieved by treating the chain as a random copolymer of C3′-endo and C2′-endo conformational isomers. The critical dependence of the characteristic ratio on the rotation about bond C3′-O3′ in the C2′-endo chain, however, obscures the interpretation of chain dimensions. The chain is also treated in higher approximation as a sequence of independent repeat units, each of which consists of six chemical bonds. The characteristic ratio obtained in this manner is 6.5 for the C3′-endo chain and 18.5 for the C2′-endo chain. Finally, the effects of partially stacked conformations in polyribonucleotides are investigated using the virtual bond treatment. Chain dimensions are calculated for random coil poly rA chains in which stacking is introduced by both noncooperative and cooperative processes.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110103
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  • 158
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    Digitale Medien
    On hydrogen bonding in amylose (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 315-318 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110124
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  • 159
    Digitale Medien
    Digitale Medien
    Far ultraviolet optical activity of saccharide derivatives. I. Xylan and cellulose acetates (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 291-301 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Optial rotatory dispersion (ORD) and Circular dichroism (CD) spectra of several β-1,4 xylan and cellulose acetates and some of their oligomers were investigated. The CD spectra proved considerably superior in terms of information content and interpretability. Comparison of the xylan and cellulose acetate series which also included partially substited cellulose acetates showed that the sign of the CD of the C(6) acetyl was negative. Likewise, the combined contribution of C(1) and C(4) to their equatorially substituted acetyls was positive (with C(1) definitely Positive) and the combined contribution of C(2)eq and C(3)eq negative. The solution conformations of both polysaccharide acetates appeared to be random. The CD of White birch xylan acetate which is substituted on the average at every tenth residue with a 4-O-methyl glucuronic acid substituent, was sensitive to it. The xylan oligomer series also illustrated that CD may be used to determine the degree of polymerization of these oligomers up to about 20.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110122
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  • 160
    Digitale Medien
    Digitale Medien
    Dielectric properties of polyelectrolytes. II. A theory of dielectric increment due to ion fluctuation by a matrix method (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 347-359 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The mean square of dipole moment of a linear macromolecule which is responsible for dielectric increment of aqueous polyelectrolyte solutions is calculated by means of a matrix method in which ion binding at discrete sites and the nearest-neighbor interaction are taken into account. On the basis of the relationship between polarization of poly-ion and fluctuation of bound counterions the present theory indicates that the loosely bound ions result in larger increment and otherwise smaller increment. Also, the theory predicts that the dielectric increment has a maximum at an intermediate monovalent-divalent ion ratio when both species coexist. These results are consistent with experiments on polyacrylic acid neutralized with NaOH and Ca(OH)2. At large contents of divalent ions the effect of chelation is also discussed.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110204
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  • 161
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    Digitale Medien
    Nuclear magnetic resonance spectra of poly(N-alkylamino acid)s (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 399-408 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 220-MHz NMR spectra of various poly (N-alkylamino acid)s are investigated. Spectra of polysarcosine recorded in various solvents showed fine splittings of the methyl and methylene bands. Comparing the spectrum with that of its model compound, the fine structure of the methyl band of polysarcosine was assigned to four dyad sequences of the cis-trans isomeric state of the main chain amide bonds. Also the methylene band was roughly divided into cis and trans bands. From the temperature dependence of the spectra of polysarcosine, a double coalescence phenomenon was observed, in which the four dyad peaks coalesced into two peaks corresponding to cis and trans, then the two peaks coalesced into one peak. Further, the approximate value of the free energy for the internal rotation of the main chain amide bond was estimated. NMR spectra of various poly(N-alkylglycine)s in methylene chloride solution were also obtained. From the comparsion of their methylene bands, the introduction of the bulky N-alkyl groups was found to increase the cis content of the amide bond.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110207
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  • 162
    Digitale Medien
    Digitale Medien
    Physico-chemical description of a condensed form of DNA (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 443-459 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: When exposed to a low pH, in various ionic strength conditions and in sufficiently dilute solutions, DNA undergoes a transition, revealed by an increase in optical density. A careful analysis shows that, associated with this transition, there is an effective decrease in absorbance, overcompensated by an increase in scattering. The conditions for the new transition can be summarized conveniently by a graph in a pH-Na+ molarity diagram. If the pH of a DNA solution is progressively lowered at constant Na+ concentration, one finds first the melting transition (I), and at lower pH values, the new transition (II). If the same experiment is performed on pre-denatured DNA, only transition II will be found. If native DNA is brought directly to the low pH conditions, without allowing it to denature irreversibly at intermediate pH values, transition II is reversible (with a small hysteresis effect). DNA, initially native, neutralized after prolonged exposures to the low pH, recovers the buoyant density value of native DNA, along with the absorption and scattering properties of the native state. The experiments are consistent with the interpretation that a new state exists in which DNA, still double stranded, assumes a very compact shape (of the order of 1500 Å in diameter for T2 DNA), with a hyperchromicity value of 10-14% above the native value. Nearly monodisperse suspensions of DNA molecule in this apparent state may be obtained only at very low concentrations (∼0.25 μg/ml). At 1 μg DNA/ml aggregation is noticeable. The possible connection with the condition of intraphage DNA is discussed.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110210
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  • 163
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    Digitale Medien
    Macromolecule-small molecule interactions; introduction of additional binding sites in polyethyleneimine by disulfide cross-linkages (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 483-491 
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    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Polyethyleneimine and its acyl derivatives have been thiolated with thiobutyrolactone and the SH groups introduced have been crosslinked in the presence of and in the absence of methyl orange, respectively. After crosslinking of the polymers, the bound methyl orange was removed. The resultant two kinds of crosslinked polymers have been examined for their ability to bind methyl orange. The polymer crosslinked in the presence of methyl orange shows more binding sites and stronger binding than does the polymer crosslinked in the absence of methyl orange. It seems, therefore, that the conformation of the polymer may be molded to provide sites that can accommodate a specific small molecule.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110213
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  • 164
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    Digitale Medien
    Masthead (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972) 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110301
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  • 165
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    Digitale Medien
    Synthesis and conformations of periodic copolypeptides of L-alanine and glycine (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 563-586 
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    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110304
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  • 166
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    Digitale Medien
    Electric birefringence and dichroism of acridine orange and methylene blue complexes with polynucleotides (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 645-652 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electro-optic measurements are reported for the polynucleotides poly A, poly U, poly G, and NaDNA, and their complexes with acridine orange (AO). Measurements were also made on the methylene blue (MB) complex with NaDNA. Poly U, poly G, and NaDNA complexes with AO as well as the NaDNA-MB complex were found to exhibit positive birefringence and perpendicular dichroism indicating the dye molecules are oriented with their long axes perpendicular to the applied electric field. The opposite was found for the AO complex with poly A, which showed positive birefringence and parallel dichroism, indicating that in this case the dye molecules are oriented with their long axes parallel to the field.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110309
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  • 167
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    Digitale Medien
    Small-angle x-ray scattering by poly-L-alanine solutions (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 679-682 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The radius of gyration and “persistence length” of poly-L-alanine, calculated from small-angle x-ray scattering data, have values of 56 Å and 44 Å, respectively, in dichloroacetic acid, and 78 Å and ∼30 Å in a 1:1 v/v mixture of trifluoroacetic acid and trifluoroethanol. This can be interpreted to mean that poly-L-alanine exists in a relatively rigid, predominantly α-helical conformation in dichloroacetic acid and in an extended, more flexible form in the mixed solvent system.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110313
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  • 168
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    Digitale Medien
    Circular dichroism of DNA: Temperature and salt dependence (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 761-779 
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    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The temperature dependence of the circular dichroism and ultraviolet absorbance of calf thymus DNA and poly dAT were measured in aqueous solutions of various 1-1 electrolytes. Although there was very little change in absorbance, the circular dichroism changed dramatically as a function of both temperature and solvent. There is a correlation of the heat of hydration of the cation and the magnitude of the temperature dependence of the circular dichroism. Our results are interpreted in terms of a large number (possibly a continuum) of intermediate secondary structures.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110404
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  • 169
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    Digitale Medien
    The crystal structure of amylose-DMSO complex (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 849-852 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110409
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  • 170
    Digitale Medien
    Digitale Medien
    Anisotropic scattering by single starch granules. II. Layered granule structureReference 1 is the first part of this series. (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 881-892 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The study of anisotropy light scattering from tapioca and potato starches has continued with the recording of more detailed experimental single-granule Hv scattering patterns and, for the first time, single-granule Vv patterns. Quantitative analysis of the higher order scattering maxima to the granule morphology, permitting an analysis of the latter in terms of a lyered structure. For tapioca starch, this analysis indicates that if layering is present at all, the layer thickness is comparable to the wavelength of the incident radiation, and most likely is considerably less than 0.5 μ in thickness. On the other hand, the potato starch morphology is characterized by a relatively coarse layering with few layers and considerable difference in the anisotropy between successive layers. The models for the two starches in best agreement with experimental data are as follows: almost perfectly spherulitic anisotropic structure with very thin shell-like layers - if any - for tapioca, and alternating layers of varying anisotropy several microns in thickness and probably simultaneously present with an isotropic center, for potato starch. The Vv pattern for tapioca starch is in agreement with this model, although its information content is lower owing to the experimental difficulty of recording higher order maxima. Suggestions for further morphological study of starches are presented.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110411
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  • 171
    Digitale Medien
    Digitale Medien
    On the Application of Polyelectrolyte “Limiting Laws” to the Helix-Coil Transition of DNA. II. The Effect of Mg++ Counterions (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 951-955 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The techniques of the previous article are here applied to the case for which the solution contains, in addition to excess uni-univalent salt, one equivalent of divalent counterions per mole nucleotide. In agreement with the melting temperature measurements of Dove and Davidson for Mg++, it is predicted that a region of uni-univalent salt concentration then exists in which (dT m/d log m A+) is negative. It is further predicted, in accord with experiment, that in the presence of divalent counterions, the helical form of DNA is much more stable than in their absence.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110503
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  • 172
    Digitale Medien
    Digitale Medien
    The determination of the thermodynamic parameter of the helix-coil transition of polypeptides by means of dipole moment measurements (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1021-1030 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The theoretical change of the mean-square dipole moment of a polypeptide during the helix-coil transition is compared with the change in helix content. It is shown that, according to the theory, the determination of the helix initiation parameter σ and the enthalpy of helix formation ΔH can be determined. Experimental data on poly-benzyl-L-gluatamate in two different solvent mixtures are given.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110507
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  • 173
    Digitale Medien
    Digitale Medien
    Optical properties and base pairing of E. coil 5S RNA (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1031-1039 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The ultraviolet absorption, optical rotatory dispersion, circular dichroism, and infrared absorption spectra of renatured 5S RNA have been measured at pH 7.0 in 0.1M NaCl at 25° and used to obtain four independent estimates of the number of base pairs. These four estimations are in reaonable agreement and average values of 28 ± 4 G.C and 13 ± 4 A.U. base pairs.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110508
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  • 174
    Digitale Medien
    Digitale Medien
    Matching of single-strand breaks to form double-strand breaks in DNA (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1116-1116 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110515
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  • 175
    Digitale Medien
    Digitale Medien
    Far-infrared spectra of copoly(-α-amino acids) (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1137-1148 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Far-infrared spectra in the region from 700 to 200 cm-1 were measured for the copolymers of L-alanine and glycine, those of L-alanine and L-valine, those of L-alanine and L-leucine, and those of L-alanine and L-phenylalanine. The observed spectra were interpreted on the basis of the analysis of the far-infrared spectra of the corresponding homopolymers, and the correlation between the conformations of the copolymers and the kinds of the component amino acids was discussed.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110603
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  • 176
    Digitale Medien
    Digitale Medien
    The circular dichroism of aromatic polypeptides: Theoretical studies of poly-L-phenylalanine and some para-substituted derivatives (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1149-1171 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We have calculated rotational strengths and circular dichroism (CD) curves for sidechain and backbone transitions in poly-L-Phenylalanine (PLP), POLY-p-amino-L-phenylalanine (PPALP), poly-p-chloro-L-phenylalanine (PPCLP), poly-o-acetyl-L-tyrosine (POALT), and poly-p-nitro-L-phenylanine (PPNLP), using methods applied previously to poly-L-tyrosine (PLT). Comparison of the theoretical CD curves with available experimental data for PLP and PPALP indicate that these polypeptides form right-handed helices with side-chain conformations similar to that of PLT. For PPNLP, where experimental data are also available, no conformational assignment could be made, as none of the calculated curves gave good agreement with experiment. Possible reasons for this lack of agreement are discussed. For the other two polypeptides, PPCLP and POALT, although no experimental data are yet available, the calculated curves indicate that an unambiguous assignment should be possible. For the conformations (RA and LA) in which the side chains are packed more loosely, there are strong similarities in the calculated CD curves of a particular conformation, regardless of the para substituent. In the tighter R1 and L1 conformations, few generalizations can be drawn, each derivative having a distinctive pattern. In PLP, PPCLP, and POALT, where the side-chain La band is in the 200-210 nm region, the L1 conformation exhibits a negative nπ* rotational strength, opposite to that expected for a left-handed helix. One must therefore be cautious about assigning the helix sense of aromatic polypeptides on the basis of the sign of the nπ* CD band. Side-chain nπ* transitions present in POALT and PPNLP were found to have small rotational strength.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110604
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  • 177
    Digitale Medien
    Digitale Medien
    Conformational studies of α-glucansContribution No. 345 from the Centre of Advanced Study in Physics, University of Madras, Madras, India. (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1379-1394 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A study of the effect of linkage on the possible conformations of di-and polysaccharides of α-D-glucose and also the probable intramolecular hydrogen bonds has been made. The differences in the nature of linkage is shown to effect the energetically preferred conformations; (1 → 2) linkages lead only to righthanded helical conformations, (1 → 3) linkages lead to extended as well as both left and righthanded helical conformations; (1 → 4) linkages lead to both right-and lefthanded wide helical conformations. The possible hydrogen bonds between adjacent residues are also dependent on the nature of the linkage. A comparison of the conformational data of α-D-glucans with those of β-D-glucans has indicated that the favored conformations and hydrogen bonds between contiguous residues in the chain are influenced by the configuration at the anomeric carbon atom in all the three types of polysaccharides. From the energy calculations a probable conformation (φM = -10°, ψM = -30°, φN = -23°, ψN = -19°) has also been proposed for crystalline mycodextran in conformity with x-ray data. This conformation contains two types of hydrogen bonds between contiguous residues one between 0-2 and 0-3 atoms at (1 → 4) linkage and the other between 0-2 and 0-4 atoms at (1 → 3) linkage in the chain. The conformation of maltose unit (-10°,-30°) that is likely to occur in the crystalline mycodextran coincides with the minimum energy conformation of maltose.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110707
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  • 178
    Digitale Medien
    Digitale Medien
    Cooperative nonenzymic base recognition - a study of interaction of oligoguanylic acid with poly C (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1395-1410 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The interaction between poly C and (Gp)nG(n = 1,2) in dilute solution was investigated spectrophotometrically in 0.1M phosphate buffer pH 7.2 under conditions unfavorable for the formation of self-associated complexes of oligoguanylic acids. Two isosbestic points were observed when poly C was titrated gradually with GpGpG, one at 232-233 mμ(in the range of 0-33% poly C) and one around 238 mμ (in the range of 50-100% poly C). The melting temperature (Tm) of the 1:1 poly C: (Gp)nG complexes (n = 1,2) of varying concentration were determined. The equilibrium properties of the 1:1 complexes can be described by two interaction parameters, namely, (i) cooperative stacking interaction between the first nearest neighbor of the adsorbed oligomer, and (ii) intrinsic association constant of the adsorbed oligomer with its polymeric site, since the cooperative helix-coil transition particularly in the smaller oligonucleotide can be described by an “all or none” model. Based on such a model the enthalpy of stacking inteaction-dependent Tm values yielded directly the sum of the enthalpy of stacking interaction and of basepairing (which is dependent on the chain length of the oligomer) and the value of S, the stability constant of a G-C pair within a helix. The enthalpy of formation of G-C pair is then calculated as -6.3 kcal/base pair either from the chain length dependent enthalpy term or from the temperature coefficient of S values. From the S value and the association constant of 1:1 GpGpGpC:GpCpCpC complex, other thermodynamic parameters such as nucleation parameter (β) and free energy of stacking interaction can be obtained.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110708
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  • 179
    Digitale Medien
    Digitale Medien
    tRNA structure and binding sites for cations (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1317-1333 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Equilibrium dialysis and electronic and nuclear resonance spectroscopy show that tRNA cooperatively binds divalent metal ions at very low concentrations (free metal concentration 3 × 10 -6 M). The first two methods show that different purified tRNAs have a very similar behavior, including initiator tRNAFmet. tRNAs with an extra arm in the clover-leaf model, however, appear to have a slightly different behavior.The binding can be described in terms of two classes of sites. The cooperative association of divalent ions binding first does not parallel a cooperative change in the hyperchromism of the tRNA, while the non-cooperative association of the second class of divalent ions corresponds to the concentrations needed to obtain a cooperative melting of the tRNA.The temperature dependence of the number of binding sites and of their binding constants is also presented.The nature of the divalent ion gives the following efficiency: for the cooperativity Co++〉Mg++〉Mn++ for the weak binding sites Mn++〉Co++〉Mg++
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110702
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  • 180
    Digitale Medien
    Digitale Medien
    Structure of β,D(1-〉4′)-xylan hydrate (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1335-1344 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A structure is proposed for xylan hydrate as a result of investigations by x-ray fiber diffraction and computer-aided chain-packing methods. The unit-cell dimensions are a = b = 9.16 Å, c (fiber axis) = 14.85Å, γ = 120° and the proposed anti-parallel chain arrangement corresponds to a space group symmetry of P3221. Left-handed threefold screw helices are stabilized in this conformation by their interaction with chains of water molecules, so that a satisfactory hydrogen-bonding scheme is achieved. The proposed structure provides an explanation of the changes in the x-ray diagram with relative humidity and yields a very good structure factors agreement. An x-ray fiber diagram corresponding to a higher hydrate (xylan dihydrate) is presented. Comments are made on the possible role of xylan in nature and in technological processes.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110703
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  • 181
    Digitale Medien
    Digitale Medien
    Studies on spin-labeled polyriboadenylic acid (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1421-1433 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Spin-labeled samples of poly rA, poly rU, and poly rG have been prepared, and physicochemical properties primarily of labeled poly rA are reported. The nitroxide radical, 4-(2-iodoacetamido)-2,2,6,6-tetramethylpiperidinooxyl, is incorporated to a greater extent in poly rA and poly rU, as compared to poly rG. No incorporation is observed in the case of poly rC. Special attention has been paid to the separation of the covalently attached labels from the free labels, and to the preservation of the integrity of the chain length of the labeled polymers. The determination of molar extinction coefficients of the three labeled polymers indicates virtually no difference from those known for the chemically unpertubed polyribonucleotides. The correlation times for the spin-labeled single stranded poly rA and poly rU have been calculated. More mobile building blocks are found in poly rU as compared to poly rA. Conformational properties of labeled poly rA in aqueous solutions have been investigated using electron spin resonance, circular dichroism, and absorption spectroscopy. The objective of the study of labeled poly rA was to examine its conformational transitions upon the uptake of protons by the adenine bases. Based on electron spin resonance data there is strong evidence that the single strand-double strand transition can take place in three steps. In addition to the already known two forms of double-stranded poly rA in acidic solution, called A and B, it is suggested that a third phase, consisting possibly of large aggregates, is involved in the transition of the less protonated double strands to those of complete protonation.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110710
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  • 182
    Digitale Medien
    Digitale Medien
    “Increased-valence” formulas for the iron-ligand bonding of some ferrohaemoglobin compounds (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1551-1565 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Valence formulas are constructed for the iron-ligand groups of the oxy-, carboxy-, nitric oxide-, and nitrosobenzene derivatives of haemoglobin. To do this, the newly developed “increased-valence” theory3 is used. The most stable of these valence formulae are able to account simply for certain iron-ligand properties, with the iron remaining essentially as ferrous, as it is in haemoglobin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110803
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  • 183
    Digitale Medien
    Digitale Medien
    Study of the interaction of polynucleotide chains with oligomers by means of chromatography (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1541-1550 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new method of measurement of the binding constant of oligonucleotides with complementary polynucleotide chains was developed using a gel filtration procedure. Data for complexing of poly U with triplets ApApA are presented and analyzed by means of a simple statistical theory of cooperative adsorption deduced by the Bethe-Guggenheim method. The complexes are triple, they contain two polymer chains bound by oligomers. The energy of stacking is found equal to 1300 cal/mol in fair agreement with earlier data of Ts'o. The energy of binding of a single triplet to both complementary chains is equal to 14,000 cal/mol.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110802
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  • 184
    Digitale Medien
    Digitale Medien
    Dielectric properties of polyelectrolytes. III. Effect of divalent cations on dielectric increment of polyacids (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1567-1582 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Dielectric dispersion of polyacrylic acid (PAA) and polystyrene sulfonic acid (PSS) was measured in the presence of divalent cations. Effects of divalent ions were studied by neutralization with varying ratios of sodium hydroxide and divalent base concentration, addition of salts of divalent cations, and neutralization with divalent bases only. Two dispersion regions were observed in all cases, i.e., low-frequency dispersion (102-104 Hz) and high-frequency dispersion (105-106 Hz). The dielectric increment increases in the presence of sodium and alkaline earth metal ions together, but not with sodium and transition metal ions. This is due to the increment of low-frequency dispersion and is attributable to the fluctuation of bound counterions which is explained by our theory previously reported.1 In the case of PAA neutralized with large fractions of divalent ions, or with divalent ions only, the increment is very small because of reduction of the fluctuation by interaction between bound ions at the neighboring sites and reduction of the effective length of polyion probably due to chelation by divalent ions. There are some differences among the effects of Mg++, Ca++, and Ba++ on dielectric increment which may result from affinity or chelating ability of these ions.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110804
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  • 185
    Digitale Medien
    Digitale Medien
    Masthead (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972) 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110901
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  • 186
    Digitale Medien
    Digitale Medien
    Normal vibrations of polyglycine II (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1841-1853 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A valence force field has been refined for single-chain polyglycine II using the known structure and four isotopic derivatives. The calculated frequencies are in good agreement with the observed. The force field is compared with that derived from polyglycine I and for the nylons.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110906
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  • 187
    Digitale Medien
    Digitale Medien
    The conformation of polycytidylic acid, polyguanylic acid, polyinosinic acid, and their helical complexes in aqueous solution from laser Raman scattering (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1855-1869 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The Raman spectra of the double helical complexes of poly C-poly G and poly I-poly C at neutral pH are presented and compared with the spectra of the constituent homopolymers.When a completely double-helical structure is formed in solution a strong sharp band at 810-814 cm-1 appears which has previously been shown to be due to the A-type conformation of the sugar-phosphate backbone chain. By taking the ratio of the intensity of the 810-814 cm-1 band to the intensity of the 1090-1100 cm-1 phosphate vibration, one can obtain an estimate of the fraction of the backbone chain in the A-type conformation for both double-stranded helices and self-stacked single chains. This type of information can apparently only be obtained by Raman spectroscopy.In addition, other significant changes in Raman intensities and frequencies have been observed and tabulated: (1) the Raman intensity of certain of the ring vibrations of guanine and hypoxanthine bases decrease as these bases become increasingly stacked (Raman hypochromism), (2) the Raman band at 1464 cm-1 in poly I is asigned to the amide II band of the cis-amide group of the hypoxanthine base. It shifts in frequency upon base pairing to 1484 cm-1, thus permitting the determination of the fraction of I-C pairs formed.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110907
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  • 188
    Digitale Medien
    Digitale Medien
    Ultrasonic absorption and relaxation spectra in aqueous bovine hemoglobin (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 1973-1984 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Measurements of the frequency and pH dependence of acoustic absorption at 0°C in aqueous solutions of freshly prepared bovine oxyhemoglobin are reported. The role of ionization and possible direct proton-transfer between proximal pairs in determining the characteristic times for the relaxation of the internal charge distribution is discussed. It is concluded that treatments which consider various classes of residues as ionizing independently will not give approximately correct relaxation spectra. A model which takes into account the coupling between the degrees of ionization of the various residues is found to give rough agreement with the observed acoustic absorption in the pH range in which the native conformation is stable.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360110916
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  • 189
    Digitale Medien
    Digitale Medien
    Masthead (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972) 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111001
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  • 190
    Digitale Medien
    Digitale Medien
    The Role of ions in the acid melting of DNA (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2033-2041 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The use of a simple chemical equilibrium and of the law of mass action leads to correct prediction when applied to the study of the role of the counterions in the process of acid melting of the DNA molecule. This approach allows an estimate to be given of the enthalpy variation per base pair associated with this process. Experiments have been carried out to test (a) the linearity of the dependence of pHm vs. 1/T; (b) the stabilizing effect of Na+ concentration. The enthalphy variation per base pair, deduced from the slope of the pHm vs. 1/T plot, and from the number of H+ bound per base pair, is in agreement with direct measurement.6,8
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111004
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  • 191
    Digitale Medien
    Digitale Medien
    Magnitude of a finite equilibration effect in analytical gel chromatography (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2125-2130 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Previous analyses of solute behavior in analytical gel chromatography1,2 have allowed for a finite equilibration time between stationary and mobile phases in estimating the magnitude of axial dispersion coefficients, but have ignored these effects in formulating the continuity equations for solute transport. We develop a more accurate theory including the equilibration effect, and show experimentally that it can be disregarded after approximately two minutes from the start of a small-zone experiment.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111012
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  • 192
    Digitale Medien
    Digitale Medien
    Hydration mobility in peptide structures (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2179-2186 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The structural behavior of hydrochlorides of poly-L-lysine and tetraglycine depends on water vapor pressure. At low relative humidities, structural rearrangements are slow. Water molecules catalyze these structural rearrangements; thus, in tetraglycine 1 H2O molecule per 10 peptide residues. Some general aspects of the mechanism of the hydration mobility in peptide structures are discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111017
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  • 193
    Digitale Medien
    Digitale Medien
    Naegeli amylodextrin and its relationship to starch granule structure. II. Role of water in crystallization of B-starchJournal Paper No. J-7181 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Proj. 1847. Supported in part by a grant from the Corn Refiners Association and by grant GM 08822 from the National Institutes of Health. (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2241-2250 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Although native B-type starch loses its sharp X-ray pattern on strong drying, the wet Nägeli amylodextrin prepared from such starch gives a sharp B-pattern, that is only slightly reduced in sharpness by complete drying. Nägeli amylodextrin dried admixed with a noncrystalline “filler” (e.g., starch sirup) gives an X-ray pattern essentially identical to that of the wet amylodextrin, except that the 16-Å (No. 1) ring is greatly reduced in sharpness and intensity. Failure of the B-structure to collapse during drying indicates that water is not intercalated between turns of a helix or otherwise required to maintain the geometry and packing arrangement of the starch molecular chains. Rather, for native starch granules or amylose fibers, water relieves intercrystallite strains and consequent crystallite distortion induced by strong drying. For Nägeli amylodextrin, the small molecules of starch sirup can penetrate the interstices between crystallites and prevent strain build-up during drying. For native starch granules, the interstitial regions are gel-like in character and less permeable to starch sirup molecules. A model for B-starch is proposed, that employs intertwined (double) helices.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111105
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  • 194
    Digitale Medien
    Digitale Medien
    Effwct of temperature on the circular dichroism spectra of polypeptides in the extended state (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2309-2316 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The circular dichroism (CD) spectra of poly-L-proline and of poly-L-glutamic acid and poly-L-lysine in their charged states have been studied as a function of temperature. The variation of CD spectra with temperature is inconsistent with the assignment of the spectrum of such charged polypetides to an unordered chain conformation, but does support our earlier assignment to a locally ordered structure - what we have called the extended helix conformation. These results also strengthen our previous assignment of the CD spectrum of an unordered chain, and indicate that three conformational states (α-helix, extended helix, and unordered) should be incorporated in our thinking about conformational transitions in polypeptides.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111109
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  • 195
    Digitale Medien
    Digitale Medien
    Far from equilibrium synthesis of “prebiotic” polymers (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2349-2356 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The existing experimental data on prebiotic nonenzymic biopolymer synthesis is used to construct a model which shows autocatalysis and highly nonlinear behavior. It is shown that far from thermodynamic equilibrium such systems may exhibit multiple steady states favoring the enhancement of the polymer population in the medium. The role of step by step chain propagation and template directed autocatalysis are studied and contrasted.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111113
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  • 196
    Digitale Medien
    Digitale Medien
    Volume effects in aqueous solutions of macromolecules containing non-polar groups (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2357-2364 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Specific volumes at 25° of aqueous solutions of poly(N-methyl acrylamide) and poly-(ethylene oxide) have been measured, and the data obtained is compared with corresponding data on low-molecular-weight compounds. The results support the notion, that the volume changes following the interaction between aliphatic groups and water are positive. They are discussed with particular reference to pressure effects on protein conformations.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111114
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  • 197
    Digitale Medien
    Digitale Medien
    Rapid kinetic studies on the conformation of single-stranded DNA (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2365-2379 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The conformational states of single-stranded calf thymus DNA were probed using the tmeperature-jump kinetic technique. A rapid decrease in transmission at 260 nm followed by a broad relaxation spectrum was observed for single-stranded DNA at 0.15M KCI, pH, 6.5 at 25°. The relaxation spectrum could also be detected as a hydrogen ion release. Sonicated samples of 103,000 daltons showed identical relaxation kinetics as unsonicated samples. The relaxation kinetics were studied as a function of temperature, pH, and salt concentration and could be interpreted as representing the melting of short, isolated folded segments. The rapid process that could not be kinetically resolved is interpreted as single-strand unstacking. Upon the addition of excess MgCl2 at pH 7.0, a hydrogen ion release from single-stranded DNA was observed that was 3.5 times greater than that observed for a comparable sample of native DNA. Evidence is presented which indicates that charge-pairs exist in folded segments that are A-T rich. There was no kinetic evidence of structures in single-stranded DNA other than single-stranded stacking and short isolated folded regions.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111115
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  • 198
    Digitale Medien
    Digitale Medien
    Poly(L-alanine): Investigation of alpha-helix and betal-sheet forms by low-temperature specific heat measurements (1.5-20°K) (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2483-2491 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: For an ideal one-dimensional solid, the low-temperature specific heat, C, is proportional to temperature T1, for an ideal two-dimensional solid C is proportional to T2. We have observed such one- and two-dimensional behavior in alpha- and beta-poly(L-alanine) in the temperature range 1.5-20°K (also intermixed with a three-dimensional behavior). A specific heat anomaly has also been observed. These measurements are important in evaluating the effective elastic constants, including hydrogen bonding, of the biopolymers. They also provide essential information for vibrational theories of poly(L-alanine), which up until now have been based on high-energy data.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111208
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  • 199
    Digitale Medien
    Digitale Medien
    Protein labeling by acetylation (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2533-2536 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method has been developed for labeling proteins by acetylation without appreciable loss in biological activity.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111212
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  • 200
    Digitale Medien
    Digitale Medien
    Electrical conductivity in the solid state of sodium salts of calf thymus DNA (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2563-2575 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A dc conductivity study of native and denatured samples of sodium salts of calf thymus DNA in the solid state was performed at different temperatures and water content. From the results obtained it appears that the major carrier of conductivity is either electronic or ionic, depending upon the temperature of the sample, the water content, and the fact that the conductivity of native samples is higher than that of the denatured ones. These results have been confirmed by dc conductivity studies of poly U and poly A.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1972.360111214
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