ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Infrared absorption and x-ray diffraction measurements have been made of D,L-copoly-γ-benzylglutamate fibers (cast from dioxane solutions) with various D/L ratios and with various degrees of polymerization. It was found that each chain of these copolymers consists of a random coil portion and an α-helix portion and that the conformation of the latter is similar to the α-helix of pure poly-γ-benzyl-L-glutamate. It was also found that the fraction of the α-helix portion increases with the degree of polymerization of the copolymer. A simplified polymerization mechanism has been proposed for mixtures of D- and L-amino acid N-carboxyanhydrides. A model of the molecular conformation of the D,L-copolypeptide chains derived from this proposed polymerization mechanism is in good agreement with infrared, x-ray, and other measurements. Based on the results of these observations, we discuss the number of L- or D-residues linked in succession that is required for initiating the formation of an α-helix during the course of polymerization.
Additional Material:
12 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360010403
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