Homooligomeric beta(3)(R)-valine peptides: transformation between C-14 and C-12 helical structures induced by a guest Aib residue

Vasantha, Basavalingappa and George, Gijo and Raghothama, Srinivasarao and Balaram, Padmanabhan (2017) Homooligomeric beta(3)(R)-valine peptides: transformation between C-14 and C-12 helical structures induced by a guest Aib residue. In: BIOPOLYMERS, 108 (1, SI).

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Abstract

Novel helical, structures unprecedented in the chemistry of alpha-polypeptides, may be found in polypeptides containing beta and gamma amino acids. The structural characterization of C-12 and C-14-helices in oligo beta-peptides was originally achieved using conformationally constrained cyclic beta-residues. This study explores the conformational characteristics of proteinogenic beta(3) residues in homooligomeric sequences and addresses the issue of inducing a transition between C-14 and C-12 helices by the introduction of a guest alpha-residue. Folded C-14-helical structures are demonstrated for the nonapeptide Boc-beta(3)(R)Val](9)-OMe by NMR methods in CDCl3-DMSO mixtures, while the peptide was found to be aggregated in CDCl3. The insertion of a guest Aib residue into an oligo-beta-valine sequence in the octapeptide model Boc-(beta(3)(R)Val)(3)Aib-(beta(3)(R)Val](4)-OMe results in well dispersed NH region in the NMR spectrum indicating folded structures in CDCl3. Structure calculations for both the peptides using NOE distance constraints support a C-14 helical structure in the homooligomer which transform into a C-12 helix on introduction of the guest Aib residue.

Item Type:	Journal Article
Publication:	BIOPOLYMERS
Additional Information:	Copy right for this article belongs to the WILEY, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	16 Sep 2017 05:48
Last Modified:	16 Sep 2017 05:48
URI:	http://eprints.iisc.ac.in/id/eprint/57840

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