Conformations of dehydrophenylalanine containing peptides: nmr studies of an acyclic hexapeptide with two delta Z-Phe residues

Chauhan, VS and Uma, K and Kaur, Paramjeet and Balaram, P (1989) Conformations of dehydrophenylalanine containing peptides: nmr studies of an acyclic hexapeptide with two delta Z-Phe residues. In: Biopolymers, 28 (3). pp. 763-771.

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Abstract

The conformation of an acyclic dehydrophenylalanine (delta Z-Phe) containing hexapeptide, Boc-Phe-delta Z-Phe-Val-Phe-delta Z-Phe-Val-OMe, has been investigated in CDCl3 and (CD3)2SO by 270-MHz 1H-nmr. Studies of NH group solvent accessibility and observation of interresidue nuclear Overhauser effects (NOEs) suggest a significant solvent-dependent conformational variability. In CDCl3, a population of folded helical conformations is supported by the inaccessibility to solvent of the NH groups of residues 3-6 and the detection of several NiH----Ni + 1H NOEs. Evidence is also obtained for conformational heterogeneity from the detection of some Ci alpha H----Ni + 1H NOEs characteristic of extended strands. In (CD3)2SO, the peptide largely favors an extended conformation, characterized by five solvent-exposed NH groups and successive Ci alpha H----Ni + 1H NOEs for the L-residues and Ci beta H----Ni + 1H NOEs for the delta Z-Phe residues. The results suggest that delta Z-Phe residues do not provide compelling conformational constraints.

Item Type:	Journal Article
Publication:	Biopolymers
Publisher:	John Wiley and Sons
Additional Information:	Copyright of this article belongs to John Wiley and Sons.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	26 Aug 2010 10:33
Last Modified:	19 Sep 2010 06:15
URI:	http://eprints.iisc.ac.in/id/eprint/31551

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