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Solid state and solution conformation of Boc-L-Met-Aib-L-Phe-OMe. Beta-turn conformation of a sequence related to an active chemotactic peptide analog

Bardi, R and Piazzesi, AM and Toniolo, C and Raj, PA and Raghothama, S and Balaram, P (1986) Solid state and solution conformation of Boc-L-Met-Aib-L-Phe-OMe. Beta-turn conformation of a sequence related to an active chemotactic peptide analog. In: International Journal of Peptide & Protein Research, 27 (3). pp. 229-238.

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Official URL: http://www.ncbi.nlm.nih.gov/pubmed/3710691

Abstract

The conformation of the peptide Boc-L-Met-Aib-L-Phe-OMe has been studied in the solid state and solution by X-ray diffraction and 1H n.m.r., respectively. The peptide differs only in the N-terminal protecting group from the biologically active chemotactic peptide analog formyl-L-Met-Aib-L-Phe-OMe. The molecules adopt a type-II beta-turn in the solid state with Met and Aib as the corner residues (phi Met = -51.8 degrees, psi Met = 139.5 degrees, phi Aib = 58.1 degrees, psi Aib = 37.0 degrees). A single, weak 4----1 intramolecular hydrogen bond is observed between the Boc CO and Phe NH groups (N---O 3.25 A, N-H---O 128.4 degrees). 1H n.m.r. studies, using solvent and temperature dependencies of NH chemical shifts and paramagnetic radical induced line broadening of NH resonances, suggest that the Phe NH is solvent shielded in CDCl3 and (CD3)2SO. Nuclear Overhauser effects observed between Met C alpha H and Aib NH protons provide evidence of the occurrence of Met-Aib type-II beta-turns in these solvents.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Munksgaard int publ ltd.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Division of Chemical Sciences > Sophisticated Instruments Facility
Date Deposited: 28 Jan 2010 07:11
Last Modified: 28 Jan 2010 07:11
URI: http://eprints.iisc.ernet.in/id/eprint/22137

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