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Conformations of dehydrophenylalanyl containing peptides. Nuclear Overhauser effect study of two acyclic

Uma, K and Chauhan, VS and Arun, Kumar and Balaram, Padmanabhan (1988) Conformations of dehydrophenylalanyl containing peptides. Nuclear Overhauser effect study of two acyclic. In: International Journal of Peptide and Protein Research, 31 (4). pp. 349-358.

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Official URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1399-...

Abstract

Two isomeric, acyclic tetrapeptides containing a Z-dehydrophenylalanine residue (Δz-Phe) at position 2 or 3, Boc-Leu-Ala-Δz-Phe-Leu-OMe (1) and Boc-Leu-Δz-Phe-Ala-Leu-OMe (2), have been synthesized and their solution conformations investigated by 270MHz 1H n.m.r. spectroscopy. In peptide 1 the Leu(4) NH group appears to be partially shielded from solvent, while in peptide 2 both Ala(3) and Leu(4) NH groups show limited solvent accessibility. Extensive difference nuclear Overhauser effect (n.O.e.) studies establish the occurrence of several diagnostic inter-residue n.O.e.s (CαjH ⇆ Ni+1H and NiH ⇆ Ni+1H) between backbone protons. The simultaneous observation of “mutually exclusive” n.O.e.s suggests the presence of multiple solution conformations for both peptides. In peptide 1 the n.O.e. data are consistent with a dynamic equilibrium between an -Ala-Δz-Phe- Type II β-turn structure and a second species with Δz-Phe adopting a partially extended conformation with Ψ values of ± 100° to ± 150°. In peptide 2 the results are compatible with an equilibrium between a highly folded consecutive β-turn structure for the -Leu-Δz-Phe-Ala- segment and an almost completely extended conformation.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to John Wiley & Sons.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 09 Nov 2010 09:33
Last Modified: 09 Nov 2010 09:33
URI: http://eprints.iisc.ernet.in/id/eprint/33532

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