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Molecular Carpentry: Piecing Together Helices and Hairpins in Designed Peptides

Das, Chittaranjan and Shankaramma, Channaveerappa S and Balaram, Padmanabhan (2001) Molecular Carpentry: Piecing Together Helices and Hairpins in Designed Peptides. In: Chemistry - A European Journal, 7 (4). pp. 840-847.

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Abstract

The design of a peptide that contains two distinct elements of secondary structure, helix and beta-hairpin, is described. Two designed 17-residue peptides: Boc-Val-Ala-Leu-Aib-Val-Ala-Leu-Gly-Gly-Leu-Phe-Val-d-Pro-Gly-Leu-Phe-Val-OMe (I) and Boc-Leu-Aib-Val-Ala-Leu-Aib-Val-Gly-Gly-Leu-Val-Val-d-Pro-Gly-Leu-Val-Val-OMe (II) have been conformationally characterized by NMR spectroscopy. Peptides I and II contain a seven-residue helical module at the N terminus and a eight-residue beta-hairpin module at the C terminus, which are connected by a conformationally flexible Gly-Gly segment. The choice of the secondarystructure modules is based upon prior crystallographic and spectroscopic analysis of the individual modules. Analysis of 500 MHz 1H NMR data, recorded as solutions in methanol, suggests that the observed pattern of chemical shifts, 3JHN¡CaH values, temperature coefficients of the NH chemical shifts, and backbone inter-residue nuclear Overhauser effects favor helical structures for residues 1 - 7 and beta-hairpin structures for residues 10 - 17. The spectroscopic data are compatible with termination of the helical segment by formation of a Schellman motif; this restricts Gly(8) to a lefthanded alpha-helical conformation. Gly(9) is the only residue with multiple conformational possibilities in f,y space. Possible orientations of the two secondary-structure modules are considered. This study validates the use of stereochemically rigid peptide modules as prefabricated elements in the construction of synthetic protein mimics.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to John Wiley & Sons, Inc
Keywords: Beta-hairpin;Conformational analysis;Helical structures;Peptides;Synthesis design;Tertiary structures
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/1336

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