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Conformation of cyclic dipeptides from empirical energy calculations
Author(s) -
Chandrasekaran R.,
Lakshminarayanan A. V.,
Mohanakrishnan P.,
Ramachandran G. N.
Publication year - 1973
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.1973.360120615
Subject(s) - chemistry , side chain , ring (chemistry) , crystallography , dipeptide , crystal structure , torsion (gastropod) , stereochemistry , amino acid , organic chemistry , polymer , medicine , biochemistry , surgery
Empirical energy calculations on cyclo‐Gly‐X with X‐ Phe, Tyr, Val, and Leu as a function of the side‐chain torsion angles χ indicate that the conformation of minimum energy are characterized by χ 1 = 60°, χ 2 = 90° for Phe and Try, χ 1 = −60° for Val and χ 1 = −60°, χ 2 = 180° and χ 1 = 60° and χ 2 = 150° for Leu. The minimum energy conformation of cyclo‐Gly‐Phe and cyclo‐Gly‐Val have the side chains of Phe and Val stacked over the poperazinedione ring as suggested by NMR and found for cyclo‐Gly‐Tyr crystal structure. In contrast, the Leu side chain is expected to exist in an extended or a quasi‐folded form.