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Synthesis and conformation of the cyclic octapeptides cyclo(Phe‐Pro) 4 , cyclo(Leu‐Pro) 4 , and cyclo[Lys(Z)‐Pro] 4
Author(s) -
Kimura Shunsaku,
Imanishi Yukio
Publication year - 1983
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.360221006
Subject(s) - chemistry , cyclic peptide , stereochemistry , conformational isomerism , peptide , residue (chemistry) , isomerization , peptide bond , crystallography , molecule , organic chemistry , biochemistry , catalysis
Cyclic octapeptides, cyclo(X‐Pro) 4 , where X represents Phe, Leu, or Lys(Z), were synthesized and their conformations investigated. A C 2 ‐symmetric conformer containing two cis peptide bonds was found in all of these cyclic octapeptides. The numbers of available conformations due to the cis – trans isomerization of Pro peptide bonds depended on the nature of the solvent and X residue: they decreased in the following order: cyclo[Lys(Z)‐Pro] 4 > cyclo(Leu‐Pro) 4 > cyclo(Phe‐Pro) 4 in CDCl 3 . 13 C spin‐lattice relaxation times ( T 1 ) of these cyclic octapeptides were measured, and the contribution of segmental mobility to T 1 was found to vary with the nature of the X residue.