Premium
The effect of adjacent charges on the kinetics of rotation of the peptide bond
Author(s) -
Gerig J. T.
Publication year - 1971
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.360101207
Subject(s) - chemistry , intramolecular force , hydrogen bond , kinetics , conformational isomerism , peptide bond , amide , population , resonance (particle physics) , crystallography , proton , peptide , stereochemistry , molecule , organic chemistry , atomic physics , biochemistry , physics , demography , quantum mechanics , sociology
The kinetics of rotation of the peptide (amide) bond in dimethylacetamide, glycine dimethylamide, N ‐acetylsarcosine, and glycylsarcosine have been studied in basic, neutral, and acidic aqueous solutions by proton magnetic resonance spectroscopy. The data indicate that the presence of nearby negative or positive charges do not greatly perturb the energetics of conformational equilibration about the amide carbon‐nitrogen bond. In N ‐acetylsarcosine and glycylsarcosine two distinguishabe conformers are present; their relative abundance is essentially 50%/50% except at low pH. It is suggested that intramolecular hydrogen bonding is responsible for deviations from this population ratio. The activation enthalpies (Δ H ‡) for rotation appear to be linearly related to the corresponding activation entropies (Δ S ‡) leading to an isokinetic temperature of about 400°K.