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Conformational studies of N ‐acetyl‐ N ′‐methylamide derivatives of α‐aminobutyric acid, norvaline, and valine. II. Conformational energy calculations and comparison with experimental results
Author(s) -
Abe Akihiro,
Yamazaki Toshimasa
Publication year - 1988
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.360270608
Subject(s) - chemistry , conformational isomerism , norvaline , vicinal , stereochemistry , side chain , computational chemistry , valine , molecule , amino acid , organic chemistry , biochemistry , polymer
Abstract Conformational analyses on a series of dipeptides CH 3 —C*O—NH—CH(R)—C*O—HN—CH 3 with side chains such as R = CH 2 CH 3 , CH 2 CH 2 CH 3 , and CH(CH 3 ) 2 are described. Calculations were carried out by using semiempirical potential energy functions of Brant et al. The results were compared with those reported by Vásquez et al. and Chuman et al., who employed the ECEPP program in their analyses. The averages of the vicinal coupling constant J NH—C α Hand the side‐chain conformer fractions p (χ 1 ) and p (χ 2 )′ were estimated therefrom for preferred conformations. The characteristic features of the experimental observations derived from the 1 H‐nmr measurements are reasonably well reproduced by these calculations.