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Stereochemistry of peptides containing 1-aminocycloheptane-1-carboxylic acid (Ac7c)

Valle, G and Crisma, M and Toniolo, C and Sudhanand, * and Sukumar, M and Balaram, P and Rao, R Balaji (1991) Stereochemistry of peptides containing 1-aminocycloheptane-1-carboxylic acid (Ac7c). In: International Journal of Peptide & Protein Research, 38 (6). pp. 511-518.

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Official URL: http://www.ncbi.nlm.nih.gov/pubmed/1819586

Abstract

The crystal structures of four peptides incorporating 1-aminocycloheptane-1-carboxylic acid (Ac7c) are described. Boc-Aib-Ac7c-NHMe and Boc-Pro-Ac7c-Ala-OMe adopt beta-turn conformations stabilized by an intramolecular 4----1 hydrogen bond, the former folding into a type-I/III beta-turn and the latter into a type-II beta-turn. In the dipeptide esters, Boc-Aib-Ac7c-OMe and Boc-Pro-Ac7c-OMe, the Ac7c and Aib residues adopt helical conformations, while the Pro residue remains semi-extended in both the molecules of Boc-Pro-Ac7c-OMe found in the asymmetric unit. The cycloheptane ring of Ac7c residues adopts a twist-chair conformation in all the peptides studied. 1H-NMR studies in CDCl3 and (CD3)2SO and IR studies in CDCl3 suggest that Boc-Aib-Ac7c-NHMe and Boc-Pro-Ac7c-Ala-OMe maintain the beta-turn conformations in solution.

Item Type: Journal Article
Additional Information: Copy right of this article belongs toNational Center for Biotechnology Information.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 20 May 2010 05:10
Last Modified: 20 May 2010 05:10
URI: http://eprints.iisc.ernet.in/id/eprint/27182

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