期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1974
卷号：71
期号：12
页码：4675-4678
DOI：10.1073/pnas.71.12.4675
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The right-handed helical fraction HL in a D,L-copolypeptide chain is evaluated by a simple probability theory for each L-fraction, p. The curves of optical rotation at a single wavelength against p for poly({gamma}-benzyl-D,L-glutamate) and D,L-copolyleucine of a series of different D:L ratios in several positive helix-solvents are calculated with a modified semi-empirical Moffitt equation. From the comparison between the rotations calculated by us and observed by Downie et al., it is shown that to reproduce the observed rotations, the minimum number of right-handed helical nuclei or sequences of L-residues appropriate to the Moffitt equation are eight and four for degrees of polymerization 320 and 1860, respectively.
关键词：helical structure ; polymers ; solvent effects ; random coil
