An observation of a folded β-Ala conformation in a model peptide:: Boc-L-Pip-β-Ala-NHCH3,X-Ray diffraction study

An X-ray crystallographic characterization of a 'locally folded' conformation of a beta-Ala residue, in a short linear peptide: Boc - L-Pip - beta-Ala - NHCH3, has been described. The critical mu torsion angle between the methylene groups of the beta-Ala adopts a typical gauche (g(-)) conformation. The urethane moiety is found in the uncommon type a. The influence of the geometrical variation of the Pip residue on beta-Ala conformation has been emphasized. (C) 1998 Elsevier Science Ltd. All rights reserved.