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Designed beta-Hairpin Peptides with Defined Tight Turn Stereochemistry

Das, Chittaranjan and Naganagowda, GA and Karle, Isabella L and Balaram, P (2001) Designed beta-Hairpin Peptides with Defined Tight Turn Stereochemistry. In: Biopolymers, 58 (3). pp. 335-346.

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Abstract

The conformational analysis of two synthetic octapeptides, Boc–Leu–Val–Val–D-Pro–L-Ala–Leu–Val–Val–OMe (1) and Boc–Leu–Val–Val–D-Pro–D-Ala–Leu–Val–Val–OMe (2) has been carried out in order to investigate the effect of beta-turn stereochemistry on designed beta-hairpin structures. Five hundred megahertz 1HNMR studies establish that both peptides 1 and 2 adopt predominantly beta-hairpin conformations in methanol solution. Specific nuclear Overhauser effects provide evidence for a type II’ beta-turn conformation for the D-Pro–L-Ala segment in 1, while the NMR data suggest that the type I’ D-Pro–D-Ala b-turn conformation predominates in peptide 2. Evidence for a minor conformation in peptide 2, in slow exchange on the NMR time scale, is also presented. Interstrand registry is demonstrated in both peptides 1 and 2. The crystal structure of 1 reveals two independent molecules in the crystallographic asymmetric unit, both of which adopt beta-hairpin conformations nucleated by D-Pro–Lala type II’ beta-turns and are stabilized by three cross-strand hydrogen bonds. CD spectra for peptides and 2 show marked differences, presumably as a consequence of the superposition of spectral bands arising from both beta-turn and beta-strand conformations.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to John Wiley & Sons, Inc
Keywords: Conformational analysis;Synthetic octapeptides;Stereochemistry;Beta-turn;Beta-strand;Beta-hairpin;Crystal structure
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Division of Chemical Sciences > Sophisticated Instruments Facility
Date Deposited: 25 Aug 2004
Last Modified: 19 Sep 2010 04:14
URI: http://eprints.iisc.ernet.in/id/eprint/1333

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