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Conformational studies of proline‐, thiaproline‐ and dimethylsilaproline‐containing diketopiperazines
Author(s) -
Cavelier Florine,
Marchand Damien,
Mbassi Patrick,
Martinez Jean,
Marraud Michel
Publication year - 2006
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/psc.767
Subject(s) - diketopiperazines , pyrrolidine , proline , heteroatom , chemistry , conformational isomerism , stereochemistry , ring (chemistry) , amino acid , molecule , biochemistry , organic chemistry
Abstract As proline plays an important role in biologically active peptides, many analogues of this residue have been developed to modulate the proportion of cis and trans conformers. A correlation between the pyrrolidine ring shape and structural properties of proline has been established. Diketopiperazine (DKP) is the model of choice to study the influence of the proline ring modification. In this contribution, cyclo(Gly‐Pro) and two analogues cyclo(Sip‐Pro) and cyclo(Thz‐Pro) have been studied with proton NMR. We showed that both analogues with heteroatoms in γ position, silicon and sulfur respectively, display a more rigid five‐member ring. The usual flexibility of proline ring is restrained in both cases and only the two C β ‐exo and C β ‐endo conformations are observed. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.