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Molecular structure of a cyclic tetrapeptide disulfide. A novel 310 helical conformation with an S-S bridge

Prasad, BV Venkataram and Ravi, A and Balaram, Padmanabhan (1981) Molecular structure of a cyclic tetrapeptide disulfide. A novel 310 helical conformation with an S-S bridge. In: Biochemical and Biophysical Research Communications, 103 (4). pp. 1138-1144.

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Abstract

The crystal structure of the cyclic peptide disulfide Boc-Cys-Pro-Aib-Cys-NHMe has been determined by X-ray diffraction. The peptide crystallizes in the space group P212121, with A = 8.646(1), B = 18.462(2), C = 19.678(3)Å and Z = 4. The molecules adopt a highly folded compact conformation, stabilized by two intramolecular 4→ 1 hydrogen bonds between the Cys (1) and Pro (2) CO groups and the Cys (4) and methylamide NH groups, respectively. The backbone conformational angles for the peptide lie very close to those expected for a 310 helix. The S-S bridge adopts a right handed twist with a dihedral angle of 82°. The structure illustrates the role of stereochemically constrained residues, in generating novel peptide conformations. Aib, α-aminoisobutyric acid; Z, benzyloxycarbonyl; Boc, t-butyloxycarbonyl; OMe, methyl ester; OBz, benzyl ester; NHMe, N-methylamide; Tosyl, p-toluenesulfonyl.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Elsevier Science.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Depositing User: Ali K S
Date Deposited: 22 Dec 2009 12:16
Last Modified: 19 Sep 2010 05:43
URI: http://eprints.iisc.ac.in/id/eprint/22699

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