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Conformations of the amino terminal tetrapeptide of emerimicins and antiamoebin in solution and in the solid state

Bardi, R and Piazzesi, AM and Toniolo, C and Antony Raj, P and Raghothama, Srinivasarao and Balaram, Padmanabhan (1986) Conformations of the amino terminal tetrapeptide of emerimicins and antiamoebin in solution and in the solid state. In: International Journal of Biological Macromolecules, 8 (4). pp. 201-206.

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Official URL: http://dx.doi.org/10.1016/0141-8130(86)90027-9

Abstract

The conformations of Boc-l-Phe-(AiB)3-OH (1) and Boc-l-Phe-(Aib)3-OMe (2) which correspond to the amino terminal sequence of the emerimicins and antiamoebins have been studied in solution using 270 MHz 1H n.m.r. In dimethyl sulphoxide solution both peptides show the presence of two strongly solvent shielded Aib NH groups, consistent with a consecutive β-turn conformation, involving the Aib(3) and Aib(4) NH groups in intramolecular 4 → I hydrogen bonds. This folded conformation is maintained for 2 in chloroform solution. Nuclear Overhauser effect studies provide evidence for a Type II Phe-Aib β-turn. An X-ray diffraction study of Boc-(d,l)-Phe-(Aib)3-OH establishes a single type III(III′) β-turn conformation with Aib(2)-Aib(3) as the corner residues. A single intramolecular 4 → I hydrogen bond between Phe(I) CO and Aib(4) NH groups is observed in the crystal. The solution conformation may incorporate a consecutive type II-III′ structure for the Phe(1)-Aib(2)-Aib(3) segment, with the initial type II β-turn being destabilized by intermolecular interactions in the solid state.

Item Type: Journal Article
Additional Information: copyright of this article belongs to Elsevier Science.
Keywords: Aib-containing peptides; emerimicins; antiamoebins; 1H n.m.r.; β-turns; X-ray diffraction; β-turn conformation.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 09 Nov 2010 09:43
Last Modified: 09 Nov 2010 09:43
URI: http://eprints.iisc.ernet.in/id/eprint/33520

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