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Solvent-induced Beta-hairpin to helix conformational transition in a designed peptide

Awasthi, Satish K and Shankaramma, SC and Raghothama, S and Balaram, P (2001) Solvent-induced Beta-hairpin to helix conformational transition in a designed peptide. In: Biopolymers, 58 (5). pp. 465-476.

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Abstract

An octapeptide containing a central Aib-Gly- segment capable of adopting -turn conformations compatible with both hairpin ( II or I ) and helical ( I) structures has been designed. The effect of solvent on the conformation of the peptide Boc-Leu-Val-Val-Aib-Gly-Leu-Val-Val-OMe (VIII; Boc: t-butyloxycarbonyl; OMe: methyl ester) has been investigated by NMR and CD spectroscopy. Peptide VIII adopts a well-defined -hairpin conformation in solvents capable of hydrogen bonding like (CD3)2SO and CD3OH. In solvents that have a lower tendency to interact with backbone peptide groups, like CDCl3 and CD3CN, helical conformations predominate. Nuclear Overhauser effects between the backbone protons and solvent shielding of NH groups involved in cross-strand hydrogen bonding, backbone chemical shifts, and vicinal coupling constants provide further support for the conformational assignments in different solvents. Truncated peptides Boc-Val-Val-Aib-Gly-Leu-Val-Val-OMe (VII), Boc-Val-Val-Aib-Gly-Leu-Val-OMe (VI), and Boc-Val-Aib-Gly-Leu-OMe (IV) were studied in CDCl3 and (CD3)2SO by 500 MHz 1H-NMR spectroscopy. Peptides IV and VI show no evidence for hairpin conformation in both the solvents. The three truncated peptides show a well-defined helical conformation in CDCl3. In (CD3)2SO, peptide VII adopts a -hairpin conformation. The results establish that peptides may be designed, which are poised to undergo a dramatic conformational transition

Item Type: Journal Article
Additional Information: The copyright of this article belongs John Wiley & Sons, Inc. Please note that the DOI link in not activated yet.
Keywords: beta hairpin;helix;conformational transition;truncated peptides;nuclear Overhauser effects;backbone chemical shifts
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Division of Chemical Sciences > Sophisticated Instruments Facility
Date Deposited: 21 Jul 2004
Last Modified: 19 Sep 2010 04:14
URI: http://eprints.iisc.ernet.in/id/eprint/1094

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