An incipient 310 helix in Piv-Pro-Pro-Ala-NHMe as a model for peptide folding

Venkatachalapathi, YV and Balaram, P (1979) An incipient 310 helix in Piv-Pro-Pro-Ala-NHMe as a model for peptide folding. In: Nature, 281 (5726). pp. 83-84.

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Abstract

The molecular mechanism of helix nucleation in peptides and proteins is not yet understood and the question of whether sharp turns in the polypeptide backbone serve as nuclei for protein folding has evoked controversy1,2. A recent study of the conformation of a tetrapeptide containing the stereochemically constrained residue alpha-aminoisobutyric acid, both in solution and the solid state, yielded a structure consisting of two consecutive beta-turns, leading to an incipient 310 helical conformation3,4. This led us to speculate that specific tri- and tetra-peptide sequences may indeed provide a helical twist to the amino-terminal segment of helical regions in proteins and provide a nucleation site for further propagation. The transformation from a 310 helical structure to an alpha-helix should be facile and requires only small changes in the phi and psi conformational angles and a rearrangement of the hydrogen bonding pattern5. If such a mechanism is involved then it should be possible to isolate an incipient 310 helical conformation in a tripeptide amide or tetrapeptide sequence, based purely on the driving force derived from short-range interactions. We have synthesised and studied the model peptide pivaloyl-Pro-Pro-Ala-NHMe (compound I) and provide here spectroscopic evidence for a 310 helical conformation in compound I.

Item Type:	Journal Article
Publication:	Nature
Publisher:	Nature Publishing Group
Additional Information:	Copyright of this article belongs to Nature Publishing Group.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	22 Feb 2010 09:56
Last Modified:	19 Sep 2010 05:55
URI:	http://eprints.iisc.ac.in/id/eprint/25636

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