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IR vibrational CD in alanyl tripeptide: Indication of a stable solution conformer
Author(s) -
Lee O.,
Roberts G. M.,
Diem M.
Publication year - 1989
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.360281009
Subject(s) - chemistry , tripeptide , conformational isomerism , aqueous solution , amide , alanine , peptide , peptide conformation , stereochemistry , infrared , computational chemistry , molecule , crystallography , organic chemistry , amino acid , biochemistry , physics , optics
Infrared vibrational CD (VCD) of a small peptide, L ‐alanyl‐ L ‐alanyl‐ L ‐alanine (Ala 3 ), and a peptide model, N‐acetyl‐ L ‐alanine‐N′‐methyl‐amide (AAMA), in the 1550–1750‐cm −1 region has been observed. The “coupled oscillator” VCD feature observed for Ala 3 in the amide I region is interpreted in terms of a solution structure stabilized by the electrostatic interaction of the zwitterionic groups. No such interactions are possible in basic aqueous solution of Ala 3 nor in AAMA in neutral solution. Thus, the coupled oscillator features are lost in the latter two cases, indicating the absence of a simple stabilized conformation.