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Temperature and pressure effects on conformational equilibria of alanine dipeptide in aqueous solution
Author(s) -
Takekiyo Takahiro,
Imai Takashi,
Kato Minoru,
Taniguchi Yoshihiro
Publication year - 2004
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.10548
Subject(s) - chemistry , conformational isomerism , intramolecular force , aqueous solution , enthalpy , hydrogen bond , dipeptide , solvent , raman spectroscopy , partial molar property , crystallography , alanine , solvent effects , stereochemistry , molecule , thermodynamics , organic chemistry , amino acid , biochemistry , physics , optics
We investigated the temperature and pressure effects on conformational equilibria of N ‐acetyl‐L‐alanine‐ N ′‐methylamide (AAlaMA) in aqueous solution by Raman spectroscopy. Scattering intensities in the skeletal stretching mode of AAlaMA in aqueous solution were decomposed into some component bands by the spectra analysis. Our results indicate that each component band for AAlaMA adopts not only the P II and α R conformations but also the C 7eq conformation. From temperature and pressure dependencies of the band intensities, we determined the enthalpy differences and the volume differences between the conformers. The C 7eq conformer is enthalpically most stable due to the intramolecular hydrogen bond. The partial molar volume of the C 7eq conformer is the smallest through the solvent‐exclusion effect rather than the solute‐solvent electrostatic interaction effect. © 2004 Wiley Periodicals, Inc. Biopolymers 73: 283–290, 2004