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Molecular and crystal structures of three monothiated analogues of the terminally blocked ala‐aib‐ala sequence of peptaibol antibiotics
Author(s) -
Bardi Renato,
Piazzesi Anna Maria,
Toniolo Claudio,
Jensen Ole E.,
Omar Rashad S.,
Senning Alexander
Publication year - 1988
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.360270504
Subject(s) - chemistry , stereochemistry , sequence (biology) , peptide , crystal structure , antibiotics , crystallography , biochemistry
The molecular and crystal structures of three monothiated analogues of the blocked L ‐Ala‐Aib‐ L ‐Ala sequence of peptaibol antibiotics, t ‐Boc‐ L ‐Ala‐Aib‐ψ(CSNH)‐ L ‐Ala‐OMe, Ac‐ L ‐Ala‐Aib‐ψ(CSNH)‐ L ‐Ala‐OMe, and Ac‐ψ(CSNH)‐ L ‐Ala‐Aib‐ L ‐Ala‐OMe, determined by x‐ray diffraction analyses, are reported. In all cases the peptide chain is folded with φ,ψ angles close to or slightly distorted from those expected for a type II β‐bend conformation. However, the 4 → 1 H‐bond distance falls within the accepted limits only for Ac‐ L ‐Ala‐Aib‐ψ(CSNH)‐ L ‐Ala‐OMe. The structures are compared with those already published for their two oxygenated analogues.