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Conformational investigations of cyclic dipeptides: Cyclo‐glycyl‐ L ‐methionyl, cyclo‐glycyl‐ D , L ‐norleucyl and cyclo‐glycyl‐ D , L ‐norvalyl
Author(s) -
Siemion I. Z.,
Picur B.
Publication year - 1984
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270220308
Subject(s) - conformational isomerism , dipeptide , stereochemistry , ring (chemistry) , ring flip , chemistry , cyclic peptide , side chain , peptide , molecule , biochemistry , organic chemistry , polymer
The E 0 rotamer of c ‐Gly‐Met has been found to be almost as equally populated as the F rotamer at low temperatures, whereas in c ‐Gly‐ D , L ‐Nle and c ‐Gly‐ D , L ‐Nvl the F rotamer predominates. The increase of the E 0 rotamer population parallels the increase of the boat diketopiperazine (DKP) ring conformation, in which Med side‐chain occupies a pseudoaxial position. Thermodynamic parameters for DKP ring inversion and for conformational transitions in the side‐chains were experimentally determined for each cyclic dipeptide investigated.