m-aminobenzoic acid inserted beta-turn in acyclic tripeptides: a peptidomimetic design

Dutt, A., Drew, M.G.B. and Pramanik, A. (2005) m-aminobenzoic acid inserted beta-turn in acyclic tripeptides: a peptidomimetic design. Tetrahedron, 61 (47). pp. 11163-11167. ISSN 0040-4020 doi: 10.1016/j.tet.2005.09.020

Abstract/Summary

X-ray diffraction studies show that peptides Boc-Leu-Aib-m-ABA-OMe (I) (Aib, alpha-aminoisobutyric acid; m-ABA, meta-aminobenzoic acid) and Boc-Phe-Aib-m-ABA-OMe, (II) adopt a type-II beta-turn conformation, solely stabilized by co-operative steric interactions amongst the amino acid residues. This type of U-turn without any intramolecular hydrogen bonding is generally referred to as an open turn. Although there are some examples of constrained cyclic peptides in which o-substituted benzenes have been inserted to mimic the turn region of the neurotrophin, a nerve growth factor, peptides I and II present novel two examples where m-aminobenzoic acid has been incorporated in the beta-turn of acyclic tripeptides. The result also demonstrates the first crystallographic evidence of a beta-turn structure containing an inserted m-aminobenzoic acid, which can be considered as a rigid gamma-aminobutyric acid with an all-trans extended configuration. (c) 2005 Elsevier Ltd. All rights reserved.