Exploring the Consequences of a Representative ``Disallowed'' Conformation of Aib on a 3(10)-Helical Fold

Tumminakatti, Shama and Reddy, Damodara N and Prabhakaran, Erode N (2015) Exploring the Consequences of a Representative ``Disallowed'' Conformation of Aib on a 3(10)-Helical Fold. In: BIOPOLYMERS, 104 (1). pp. 21-36.

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Abstract

The structural effects of a representative ``disallowed'' conformation of Aib on the 3(10)-helical fold of an octapeptidomimetic are explored. The 1D (H-1, C-13) & 2D NMR, FT-IR and CD data reveal that the octapeptide 1, adopts a 3(10)- helical conformation in solution, as it does in its crystal structure. The C-terminal methyl carboxylate (CO2Me) of 1 was modified into an 1,3-oxazine (Oxa) functional group in the peptidomimetic 2. This modification results in the stabilization of the backbone of the C-terminal Aib (Aib(star)-Oxa) of 2, in a conformation (phi, psi = 180, 0) that is natively disallowed to Aib. Consequent to the presence of this natively disallowed conformation, the 3(10)- helical fold is not disrupted in the body of the peptidomimetic 2. But the structural distortions that do occur in 2 are primarily in residues in the immediate vicinity of the natively disallowed conformation, rather than in the whole peptide body. Non-native electronic effects resulting from modifications in backbone functional groups can be at the origin of stabilizing residues in natively disallowed conformations. (C) 2014 Wiley Periodicals, Inc. Biopolymers

Item Type:	Journal Article
Publication:	BIOPOLYMERS
Publisher:	WILEY-BLACKWELL
Additional Information:	Copy right for this article belongs to the WILEY-BLACKWELL, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA
Keywords:	peptides; disallowed conformations; 3(10)-helix; Aib rich peptides; oxazines; electronic effects; solution structure
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	03 Sep 2015 06:52
Last Modified:	03 Sep 2015 06:52
URI:	http://eprints.iisc.ac.in/id/eprint/52299

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