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Rotational isomerism of N ‐acetylamino acid methylamides having serine, tyrosine, histidine, and proline residues as revealed by Raman spectroscopy
Author(s) -
Koyama Yasushi,
Uchida Hisaaki,
Oyama Shigeru,
Iwaki Tetsuo,
Harada Kimihiko
Publication year - 1977
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.1977.360160814
Subject(s) - chemistry , histidine , raman spectroscopy , serine , hydrogen bond , stereochemistry , intermolecular force , proline , aqueous solution , tyrosine , amino acid , crystallography , molecule , organic chemistry , biochemistry , enzyme , physics , optics
Rotational isomerism of N ‐acetylamino acid methylamides having serine, tyrosine, histidine, and proline residues was investigated by means of Raman spectroscopy. The Raman spectra of each compound for solid states (crystalline or glassy) as well as for aqueous solution were compared with each other. Different kinds of rotational isomers were found to exist in the different solid states; three such solid states for N ‐acetylserine methylamide, two for N ‐acetyltyrosine methylamide, and one for N ‐acetylhistidine methylamide were found in the present investigation. Additional rotational isomers were found to exist in aqueous solutions. The results indicated that the inherent relative stability of the rotational isomers differs little and is very dependent on intermolecular interaction, especially that due to hydrogen bonds. The possible molecular conformations are discussed on the basis of x‐ray results now available both for the present compounds and for proteins.