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Comparison of proline and N ‐methylnorleucine induced conformational equilibria in cyclic pentapeptides
Author(s) -
Weiβhoff Hardy,
Wieprecht Torsten,
Henklein Peter,
Frömmel Cornelius,
Antz Christof,
Mügge Clemens
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00469-3
Subject(s) - chemistry , peptide bond , isomerization , stereochemistry , cis–trans isomerism , cyclic peptide , peptide , conformational isomerism , nuclear magnetic resonance spectroscopy , molecule , catalysis , organic chemistry , biochemistry
The cyclic, imido acid containing pentapeptides cyclo(Asp‐Trp‐(NMe)Nle‐Asp‐Phe) (cpp[NMeNle 3 ]) and cyclo(Asp‐Trp‐Pro‐Asp‐Phe) (cpp[Pro 3 ]) have been investigated by 1 H‐NMR spectroscopy in DMSO and by restrained molecular dynamics methods. The spectra indicate the existence of at least four cis/trans isomers for cpp[NMeNle 3 ] and two cis/trans isomers for cpp[Pro 3 ]. In addition to the imido peptide bonds, cpp[NMeNle 3 ] shows cis/trans isomerization of the Asp 4 ‐Phe 5 and Phe 5 ‐Asp 1 peptide bonds whereas only the Phe 5 ‐Asp 1 peptide bond isomerizes in the Pro‐containing peptide. In cpp[Pro 3 ] all cis bonds are centred in βVIb turns. Also, cpp[NMeNle 3 ] prefers backbone angles around the cis bonds which are rather similar to the angles of a βVIb turn. The higher number of cis/trans isomers and slight deviations in the backbone angles of comparable isomers of both peptides are caused by an enhanced flexibility of cpp[NMeNle 3 ] due to the possibility of the φ‐(NMe)Nle rotation.