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Peptide hybrids containing alpha- and beta-amino acids: Structure of a decapeptide beta-hairpin with two facing beta-phenylalanine residues

Karle, Isabella L and Gopi, Hosahudya N and Balaram, Padmanabhan (2001) Peptide hybrids containing alpha- and beta-amino acids: Structure of a decapeptide beta-hairpin with two facing beta-phenylalanine residues. In: Proceedings of the National Academy of Sciences of the United States of America, 98 (7). pp. 3716-3719.

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Abstract

A beta-hairpin conformation has been characterized in crystals of the decapeptide t-butoxycarbonyl-Leu-Val-betaPhe-Val-DPro-Gly-Leub Phe-Val-Val-methyl ester [bPhe; (S)-b3 homophenylalanine] by x-ray diffraction. The polypeptide chain reversal is nucleated by the centrally positioned DPro-Gly segment, which adopts a type-I’ beta-turn conformation. Four intramolecular cross-strand hydrogen bonds stabilize the peptide fold. The betaPhe(3) and betaPhe(8) residues occupy facing positions on the hairpin, with the side chains projecting on opposite faces of the beta-sheet. At the site of insertion of beta- residues, the polarity of the peptide units along each strand reverses, as compared with the alpha-peptide segments. In this analog, a small segment of a polar sheet is observed, where adjacent CO and NH groups line up in opposite directions in each strand. In the crystal, an extended beta-sheet is formed by hydrogen bonding between strands of antiparallel pairs of beta-hairpins. The crystallographic parameters for C65H102N10O13z 3H2O are: space group P212121; a 5 19.059(8) Å, b 5 19.470(2) Å, c 5 21.077(2) Å; Z 5 4; agreement factor R1 5 9.12% for 3,984 data observed >4s(F) and a resolution of 0.90 Å.

Item Type: Journal Article
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 25 Aug 2004
Last Modified: 19 Sep 2010 04:14
URI: http://eprints.iisc.ernet.in/id/eprint/1327

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