论文信息 - Conformational aspects of polypeptides. XVIII. Conformational studies of oligopeptides derived from L‐alanine

Conformational aspects of polypeptides. XVIII. Conformational studies of oligopeptides derived from L‐alanine

The conformations of oligopeptides derived from L‐alanine and co‐oligomers of L‐alanine with γ‐methyl‐L‐glutamate were studied in several solvents via optical rotation and far‐ultraviolet spectroscopy. Calculated values for optical rotation based on model compounds were compared with experimental values for the oligomers. In trifluoroacetic and dichloroacetic acids, the oligomers and co‐oligomers exhibit rotations in close agreement with predicted values based on model compounds. Thus, in these solvents only nonhelical conformations exist. In trifluoroethanol, the experimental points of molar rotation for the pentamer and larger oligomers no longer follow the predicted values. In addition, the benzyloxycarbonyl and acetyl cononamers show b0 values of about −150, which demonstrates the presence of stable helical forms for these peptides. We also examined the molar extinction coefficients of oligopeptides in the 190 mμ region and determined the values for nonhelical peptide groups. The molar extinction coefficients per amide bond for the benzyloxycarbonyl and acetyl cononamers show extensive hypo‐chromism, once again indicating the presence of stable helices for these compounds in trifluoroethanol.

M. Goodman | M. Langsam | I. Rosen

[1] M. Goodman,et al. Conformational aspects of polypeptides. XVII. Synthesis of oligomers and co‐oligomers derived from L‐alanine and L‐glutamic acid , 1966 .

[2] P. Doty,et al. A Conformation Examination of Poly-L-alanine and Poly-D,L-alanine in Aqueous Solution , 1963 .

[3] M. Goodman,et al. Conformational aspects of polypeptides. VIII. Helical assignments via far ultraviolet absorption spectra and optical activity , 1963 .

[4] M. Goodman,et al. Conformational Aspects of Synthetic Polypeptides. VI. Hypochromic Spectral Studies of Oligo-γ-Methyl-L-Glutamate Peptides , 1962 .

[5] E. Schmitt,et al. Conformational Aspects of Polypeptides. V. Molar Rotational Model Compounds for Poly-γ-methyl L-Glutamate , 1962 .

[6] E. Schmitt,et al. Conformational Aspects of Polypeptides. IV.1 Folded and Associated Forms of Oligomeric Peptides Derived from γ-Methyl Glutamate , 1962 .

[7] P. Doty,et al. The far ultraviolet absorption spectra of polypeptide and protein solutions and their dependence on conformation. , 1961, Proceedings of the National Academy of Sciences of the United States of America.

[8] K. Imahori,et al. Ultraviolet absorption spectra of poly-L-glutamic acid , 1959 .