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Multiple interconverting conformers of the cyclic tetrapeptide tentoxin, [ cyclo ‐( L ‐MeAla 1 ‐ L ‐Leu 2 ‐MePhe[(Z)Δ] 3 ‐Gly 4 )], as seen by two‐dimensional 1 H‐nmr spectroscopy
Author(s) -
Pinet Eric,
Neumann JeanMichel,
Dahse Ingo,
Girault Guy,
André François
Publication year - 1995
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.360360204
Subject(s) - chemistry , tetrapeptide , conformational isomerism , stereochemistry , crystallography , peptide , molecule , biochemistry , organic chemistry
Abstract The conformations of the phytotoxic cyclic tetrapeptide tentoxin [cyclo‐( L ‐MeAla 1 ‐ L ‐Leu 2 ‐MePhe[(Z)Δ] 3 ‐Gly 4 )] have been studied in aqueous solution by two‐dimensional proton nmr at various temperatures. Contrary to what is observed in chloroform, tentoxin exhibits multiple exchanging conformations in water. Aggregation phenomena were also observed. Four conformations with different proportions (51, 37, 8, and 4%) were observed at −5°C. Models were constructed from nmr parameters and restrained molecular dynamics simulations. All the models exhibit cis ‐ trans ‐ cis ‐ trans conformation of the amide bond sequence. The conversion from one form to another is accomplished by a conformational peptide flip consisting of a 180° rotation of a nonmethylated peptide bond. © 1995 John Wiley & Sons, Inc.