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An Unusual C–H . . . O Hydrogen Bond Mediated Reversal of Polypeptide Chain Direction in a Synthetic Peptide Helix

Aravinda, S and Shamala, N and Pramanik, Animesh and Das, Chittaranjan and Balaram, P (2000) An Unusual C–H . . . O Hydrogen Bond Mediated Reversal of Polypeptide Chain Direction in a Synthetic Peptide Helix. In: Biochemical and Biophysical Research Communications, 273 (3). pp. 933-936.

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An unusual C-terminal conformation has been detected in a synthetic decapeptide designed to analyze the stereochemistry of helix termination in polypeptides. The crystal structure of the decapeptide Boc-Leu-Aib-Val-Ala-Leu-Aib-Val-DAla-DLeu-Aib-OMe reveals a helical segment spanning residues 1–7 and helix termination by formation of a Schellman motif, generated by DAla(8) adopting the left-handed helical (aL) conformation. The extended conformation at DLeu(9) results in a compact folded structure, stabilized by a potentially strong C-H . . . O hydrogen bond between Ala(4) CaH and DLeu(9) CO. The parameters for C-H . . . O interaction are Ala(4) CaH. . O=C DLeu(9) distance 3.27 Å, Ca-H . . O angle 176°, and O . . Ha distance 2.29 Å. This structure suggests that insertion of contiguous D-residues may provide a handle for the generation of designed structures containing more than one helical segment folded in a compact manner.

Item Type: Journal Article
Publication: Biochemical and Biophysical Research Communications
Publisher: Academic Press
Additional Information: Copyright for this article belongs to Academic Press
Keywords: C-H . . . O hydrogen bond;Conformational analysis;Helix termination;Peptide design;Schellman motif;X-ray structure
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Division of Physical & Mathematical Sciences > Physics
Date Deposited: 26 Aug 2004
Last Modified: 19 Sep 2010 04:14
URI: http://eprints.iisc.ac.in/id/eprint/1348

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