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Structural Analysis of Peptide Helices Containing Centrally Positioned Lactic Acid Residues

Aravinda, S and Shamala, N and Das, Chittaranjan and Balaram, P (2002) Structural Analysis of Peptide Helices Containing Centrally Positioned Lactic Acid Residues. In: Biopolymers, 64 (5). pp. 255-267.

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Abstract

The effect of insertion of lactic acid (Lac) residues into peptide helices has been probed using specifically designed sequences. The crystal structures of 11-residue and 14-residue depsipeptides Boc–Val–Val–Ala–Leu–Val–Lac–Leu–Aib–Val–Ala–Leu–OMe (1) and Boc–Val–Ala–Leu–Aib–Val–Ala–Leu–Val–Lac–Leu–Aib–Val–Ala–Leu–OMe (3), containing centrally positioned Lac residues, have been determined. The structure of an 11-residue peptide Boc–Val–Ala–Leu–Aib–Val–Ala–Leu–Aib–Val–Ala–Leu–OMe (2), analog of a which is an amide previously determined Lac-containing depsipeptide, Boc–Val–Ala–Leu–Aib–Val–Lac–Leu–Aib–Val–Ala–Leu–OMeI. L. Karle, C. Das, and P. Balaram, Biopolymers, Vol. 59, (2001) pp. 276–289], is also reported. Peptide 1 adopts a helical fold, which is stabilized by mixture of 431 and 531 hydrogen bonds. Peptide 2 adopts a completely alpha-helical conformation stabilized by eight successive 531 hydrogen bonds. Peptide 3 appears to be predominately alpha-helical, with seven 531 hydrogen bonds and three 431 interaction interspersed in the sequence. In the structure of peptide 3 in addition to water molecules in the head-to-tail region, hydration at an internal segment of the helix is also observed. A comparison of five related peptide helices, containing a single Lac residue, reveals that the hydroxy acid can be comfortably accommodated at interior positions in the helix, with the closest C=O. . .O distances lying between 2.8 and 3.3 A°.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to John Wiley & Sons, Inc
Keywords: Depsipeptides;alpha-helix;Lactic acid;x-ray crystal structures
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 11 Aug 2004
Last Modified: 19 Sep 2010 04:14
URI: http://eprints.iisc.ernet.in/id/eprint/1252

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