Premium
Thermodynamics of solvation for methylproline peptides
Author(s) -
Madison Vincent,
Delaney Norma G.
Publication year - 1983
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.360220309
Subject(s) - chemistry , solvation , chloroform , carbon tetrachloride , intermolecular force , hydrogen bond , conformational isomerism , solvent , tripeptide , peptide , dilution , computational chemistry , thermodynamics , organic chemistry , molecule , biochemistry , physics
We have determined thermodynamic parameters for transfer of N ‐acetyl, N ′‐methylamide derivatives of proline and methylprolines from carbon tetrachloride and from chloroform to water. The hydrophilic nature of the diamide model peptides is demonstrated by the negative free energies and enthalpies for transfer. Chloroform solvates the peptides considerably better than carbon tetrachloride. Heats of dilution in carbon tetrachloride arise from disruption of intermolecular peptide–peptide hydrogen bonds. After extrapolation to dilute solution, differences in thermodynamic parameters among the isomeric mono‐methylproline peptides are correlated with the population of the intramolecularly hydrogen‐bonded C 7 conformer in the nonpolar solvent. However, the thermodynamic parameters aslo reflect differences in solvation due to the proximity of the two peptide groups and the side chain.