Premium
The optical rotatory properties of poly‐γ‐ D ‐glutamic acid
Author(s) -
Marlborough D. I.
Publication year - 1973
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1973.360120512
Subject(s) - optical rotatory dispersion , chemistry , maxima and minima , ionization , dispersion (optics) , polymer , glutamic acid , wavelength , crystallography , spectral line , amino acid , stereochemistry , circular dichroism , physics , organic chemistry , optics , biochemistry , quantum mechanics , ion , mathematical analysis , mathematics
Measurement of the optical rotatory dispersion spectra of poly‐γ‐ D ‐glutamic acid (obtained from Bacillus anthracis ) dawn to 200 nm wavelength reveal difference between the unionized and ionized froms. The profile of the unionized polyacid shows similarities to those obtained for α‐helical polypeptides, although with displaced frequencies of the respective maxima and minima. It is suggested that the relative position and magnitudes of the Cotton effect are consistent with a helical structure such as proposed by Rydon (J. Chem. Soc., 1964 , 1328). The optical rotatory dispersion spectrum of the ionized from resembles those obtained from the β‐chain from of α‐ L polypeptides. From model‐building studies an extended chain similer to the β‐from would seen the most reasonable structure for the ionized poly‐γ‐acid to adopt, since the charged groups in such a conformation would be at their maximal distances from each other. Such an ordered structure for a polymer is consistent with the hypotheses put forward in the recent literature that charged polypeptides adopt ordered rather than random‐coiled conformations.