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Rǒle des electrons π des fonctions amide et ester dans les peptides et depsipeptides
Author(s) -
Boussard G.,
Marraud M.
Publication year - 1981
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.1981.360200112
Subject(s) - chemistry , amide , depsipeptide , valinomycin , stereochemistry , residue (chemistry) , peptide , medicinal chemistry , crystallography , organic chemistry , ion , biochemistry
Abstract The IR data for the R 1 CO‐O‐CHR 2 ‐CO‐NHR 3 derivatives are interpreted in terms of a H…π interaction involving the NH bond and the π orbitals of the ester function and giving rise to a high ν(CO) frequency and a low ν frequency. The resulting molecular conformation corresponds to the angular values ϕ # −90°, ψ # 0°. The H…π interaction in MeCO‐L‐Lac‐NHMe is highly destabilized by water and aprotic solvents but is retained in methanol. Considering the high ν(CO) ester or amide frequency of the middle function in β‐folded depsipeptide or peptide sequences, it may be supposed that the residue indexed i + 2 in β turns experiences a H…π interaction which has a stabilizing effect on β turns. Some examples concerning valinomycin and some model compounds are discussed.