The crystal and molecular structure of benzyloxycarbonyl-a-amino-isobutyryl-L-prolyl-methylamide. The observation of an X2-Pro3 Type III b-turn

Prasad, BV Venkataram and Shamala, N and Nagaraj, R and Chandrasekaran, R and Balaram, P (1979) The crystal and molecular structure of benzyloxycarbonyl-a-amino-isobutyryl-L-prolyl-methylamide. The observation of an X2-Pro3 Type III b-turn. In: Biopolymers, 18 (7). 1635 -1646.

PDF fulltext.pdf - Published Version Restricted to Registered users only Download (593kB) | Request a copy

Abstract

The crystal and molecular structure of N-benzyloxycarbonyl-a-aminoisobutyryl-L-prolyl methylamide, the amino terminal dipeptide fragment of alamethicin, has been determined using direct methods. The compound crystallizes in the orthorhombic system with the space group P212-21. Cell dimensions are a = 7.705 A, b = 11.365 A, and c = 21.904 A. The structure has been refined using conventional procedures to a final R factor of 0.054. The molecular structure possesses a 4 - 1 intramolecular N-H--0 hydrogen bond formed between the CO group of the urethane moiety and the NH group of the methylamide function. The peptide backbone adopts the type 111 P-turn conformation, with 42 = -51.0°, +* = -39.7",&j = -65.0', $3 = -25.4'. An unusual feature is the occurrence of the proline residue at position 3 of the P-turn. The observed structure supports the view that Aib residues initiate the formation of type 111 @-turn conformations. The pyrrolidine ring is puckered in Cy-exo fashion.

Item Type:	Journal Article
Publication:	Biopolymers
Publisher:	John Wiley and Sons
Additional Information:	Copyright of this article belongs to John Wiley and Sons.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	22 Feb 2010 10:00
Last Modified:	19 Sep 2010 05:55
URI:	http://eprints.iisc.ac.in/id/eprint/25634

Actions (login required)

View Item