Conformations and Mitochondrial Uncoupling Activity of Synthetic Emerimicin Fragments

Raj, Antony P and Das, Manoj K and Balaram, P (1988) Conformations and Mitochondrial Uncoupling Activity of Synthetic Emerimicin Fragments. In: Biopolymers, 27 (4). pp. 683-701.

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Abstract

Several amino terminal fragments of the emerimicins $(Ac-{Phe}^1-{Aib}^2-{Aib}^3-{Aib}4-{Va1}^5-{Gly}^6-{Leu}^7-{Aib}^8-{Aib}^9-{Hyp}^{10}-{Gln}^{11}-D-{Iva}^{12}-{Hyp}^{13}-Ala/{Aib}^{14}-{Phol}^{15})$ ranging in length from five to ten residues have been synthesized. Nuclear magnetic resonance studies have been carried out on the 1-5, 6-10, 1-6, 1-7, 1-8, 1-9, and 1-10 fragments. The number of solvent-shielded NH groups in $CD{Cl}_3$ solutions for 1-5, 1-6, 1-7, 1-8, 1-9, and 1-10 indicate that $3_{10}$-helical structures are favored in this solvent. In ${({CD}_3)}_2SO$, an additional NH group, assigned to Aib(3) NH is solvent exposed in the fragments longer than six residues, suggesting partial unfolding of the N-terminal \beta-turn or transition to an \alpha-helical conformation. The data for fragment 6-10 are consistent with a conformation having a single Leu-Aib \beta-turn. Infrared studies suggest an increase in the number of intramolecular hydrogen bonds with increasing peptide chain length. Appreciable mitochondrial uncoupling activity is observed for peptides with a chain length of at least seven residues. The order of efficiencies of the fragments is 1-7 < 1-8 - 1-10 < 1-9, with the decapeptide exhibiting anomalously low uncoupling activity.

Item Type:	Journal Article
Publication:	Biopolymers
Publisher:	John Wiley & Sons, Inc.
Additional Information:	Copyright for this article belongs to John Wiley & Sons, Inc.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	25 Feb 2005
Last Modified:	19 Sep 2010 04:18
URI:	http://eprints.iisc.ac.in/id/eprint/2847

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