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The X‐Pro peptide bond as an nmr probe for conformational studies of flexible linear peptides
Author(s) -
Grathwohl Christoph,
Wüthrich Kurt
Publication year - 1976
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.1976.360151012
Subject(s) - chemistry , peptide , peptide bond , side chain , nuclear magnetic resonance spectroscopy , crystallography , stereochemistry , nmr spectra database , spectral line , organic chemistry , biochemistry , physics , astronomy , polymer
The equilibrium between the cis and trans forms of X‐Pro peptide bonds can readily be measured in the 13 C nmr spectra. In the present paper we investigate how observation of this equilibrium could be used as an nmr probe for conformational studies of flexible polypeptide chains. The experiments include studies by 13 C nmr of a series of linear oligopeptides containing different X‐ L ‐Pro peptide bonds, with X = Gly, L ‐Ala, L ‐Leu, L ‐Phe, D ‐Ala, D ‐Leu, and D ‐Phe. Overall the study confirms that X‐Pro peptide bonds can generally be useful as 13 C nmr probes reporting the formation of nonrandom conformation in flexible polypeptide chains. It was found that the cis – trans equilibrium of X‐Pro is greatly affected by the side chain of X and the configuration of the α‐carbon atom of X. On the basis of these observations some general rules are suggested for a practical applications of the X‐Pro nmr probes in conformational studies of polypeptide chains.