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*-Oxa) of 2, in a conformation (phi, =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 (Pept Sci) 104: 21-36, 2015.

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:	04 Mar 2015 12:45
Last Modified:	04 Mar 2015 12:45
URI:	http://eprints.iisc.ac.in/id/eprint/50993

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