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  • Polymer and Materials Science  (4)
  • 1975-1979  (4)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Differentiation between the α-helical and coillike conformations of poly(L-glutamic acid) in aqueous solution through binding of pinacyanol (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 2267-2277 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pinacyanol in the presence of an excess of poly(L-glutamic acid) [polymer/dye ratio (P/D) 〉 10] exhibits different absorption spectra in the visible region when bound to the slightly charged polypeptide in the α-helical conformation or to the nearly completely dissociated polypeptide in the coillike conformation. These spectra reveal aggregation of the dye bound to the macromolecular chain in both conformations, although in the coillike one different kinds of aggregates may be present. Dye binding is accompanied by the appearance of CD bands in the visible region which are also different for the α-helical and the coillike conformations. The aggregates formed in the presence of the latter change slowly in time and seem to induce some conformational changes in the polypeptide chain. Furthermore, they have been found to be, at least partially, stable with respect to a subsequent reversal to the α-helical conformation. All results could be qualitatively interpreted assuming that in the coillike conformation, ordered regions exist along the chain as proposed by Krimm and Tiffany.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180914
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  • 2
    Electronic Resource
    Electronic Resource
    Circular dichroism of the complex between N-N′-diethylpseudoisocyanine and sodium poly(L-glutamate) in aqueous solutions (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 33-41 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the presence of sodium poly(L-glutamate) at pH = 7.5 the dye pseudoisocyanine in dilute aqueous solution (Cd = 1.10 × 10-5 M) and low P/D values exhibits an absorption spectrum with a very sharp red-shifted J-band. Under the same conditions circular dichroism (CD) in the visible region is observed with an extremely sharp peak at the position of the J-band. At pH = 4.6, where the polypeptide is in the α-helix conformation, no such J-band is observed and no CD spectrum can be detected at the same P/D values. CD spectra in the uv range demonstrate that the occurrence of the dye-polypeptide complex which gives rise to the J-band at slightly alkaline pH is not accompanied by a conformational transition of the polypeptide towards the α-helical form.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160104
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  • 3
    Electronic Resource
    Electronic Resource
    Dielectric properties of maleic acid-ethylene copolymer in salt-free aqueous solutions (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 641-651 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric behavior of maleic acid-ethylene copolymer solutions has been investigated at different polymer concentrations and two degrees of neutralization α′. It is shown that this behavior is analogous to that of ordinary polyacids. Also the experimental data can be explained in terms of the van der Touw-Mandel theory, but at low α′ a possible contribution from motion of negative charges (in turn related to bound proton fluctuations) has to be taken into account. The dielectric results suggest that the formation of intramolecular hydrogen bonds has an influence on the change of the average dimensions of the chain with increasing α′. This seems to be confirmed by viscosity data.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1978.180160406
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  • 4
    Electronic Resource
    Electronic Resource
    Dielectric behavior of aqueous solutions of sodium polyphosphates of low degree of polymerization (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 773-781 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric relaxation behavior of three sodium polyphosphates with different but low degrees of polymerization in aqueous solution (without salt) has been investigated between 8 kHz and 100 MHz. The highest molecular weight sample (DP 338) exhibits two dispersion regions as is generally observed with synthetic polyelectrolytes at higher degrees of polymerization and is interpreted, according to the theory of van der Touw and Mandel, by attributing a certain flexibility to the polymer chain. The experimentally determined relaxation time of the high-frequency dispersion is in fair agreement with the theoretically calculated value. For the lowest molecular weight sample (DP 112) the experimental results can best be described by a single dispersion curve pointing to a rigid, more or less stretched, conformation of the polyion in agreement with theoretical predictions. For the sample of intermediate molecular weight (DP 198) the situation is borderline as it is possible to describe the relaxation behavior by either one or two dispersion regions; it is, however, concluded from an analysis of the dielectric results that the average conformation is rather extended, but not completely rigid.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180140501
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