Enkephalin Analogs. Introduction of Stereochemical Constraints, Metal Binding Sites and Fluorescent Groups

Nagaraj, R and Sudha, TS and Shivaji, S and Balaram, P (1979) Enkephalin Analogs. Introduction of Stereochemical Constraints, Metal Binding Sites and Fluorescent Groups. In: FEBS Letters, 106 (2). pp. 271-274.

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Abstract

There has been considerable speculation on the biologically active conformations of the enkephalins and their possible structural similarity to the opiates [1- 4]. A number of models have been proposed on the basis of theoretical calculations [2] and computer modelling [3]. Recent NMR studies suggest a high degree of conformational flexibility at ${Gly}^2$ and ${Gly}^3$ implying that a favoured conformation does not exist in aqueous solution [5]. The replacement of the Gly residues by Aib residues will greatly restrict the available conformations at positions 2 and 3 of the pentapeptides and may thereby allow a better definition of the steric requirements for biological activity. This approach appears particularly attractive in view of the extremely well defined conformations adopted by Aib containing peptides [6 -10]. An earlier report described the synthesis of ${Aib}^2$-${Met}^3$-enkephalin-amide [11]. Here we present the preparation and compare the biological properties of the ${Aib}^2$, ${Aib}^3$ and ${Aib}^2-{Aib}^3 {Met}^5$-enkephalin derivatives. The properties of 3-nitro-Tyr analogs, designed to bind paramagnetic NMR shift probes and a fluorescent ${Aib}^2$ analog developed for studies of receptor interactions, are also described.

Item Type:	Journal Article
Publication:	FEBS Letters
Publisher:	Elsevier
Additional Information:	Copyright for this article belongs to Elsevier Science Ltd.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	20 Apr 2005
Last Modified:	19 Sep 2010 04:18
URI:	http://eprints.iisc.ac.in/id/eprint/3083

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