Complex carbohydrates: 2. The modes of binding of complex carbohydrates to concanavalin A - a computer modelling approach

Sekharudu, Y Chandra and Biswas, Margaret and Rao, VSR (1986) Complex carbohydrates: 2. The modes of binding of complex carbohydrates to concanavalin A - a computer modelling approach. In: International Journal of Biological Macromolecules, 8 (1). pp. 9-19.

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Abstract

The probable modes of binding of some complex carbohydrates, which have the trimannosidic core structure (Man3GlcNAc2), to concanavalin A (Con A) have been determined using a computer modelling technique. These studies show that Con a can bind to the terminal mannose residues of the trimannosidic core structure and to the internal mannosyl as well as to the terminal N-acetylglucosamine residues of the N-acetylglucosamine substituted trimannosidic core structure. The oligosaccharide with terminal mannose residues can bind in its minimum energy conformers, whereas the oligosaccharide with internal mannosyl and terminal N-acetylglucosamine residues can bind only in higher energy conformers. In addition the former oligosaccharide forms more hydrogen bonds with Con A than the latter. These results suggest that, for these oligosaccharides, the terminal mannose residue has a much higher probability of reaching the binding site than either the internal mannosyl or the terminal N-acetylglucosamine residues. The substitution of a bisecting N-acetylglucosamine residue on these oligosaccharides, affects significantly the accessibility of the residues which bind to Con A and thereby reduces their binding affinity. It thus seems that the binding affinity of an oligosaccharide to Con A depends not only on the number of sugar residues which possess free 3-, 4- and 6-hydroxyl groups but also on the accessibility of these sugar residues to Con A. This study also reveals that the sugar binding site of Con A is small and that the interactions between Con A and carbohydrates are extended slightly beyond the single sugar residue that is placed in the binding site.

Item Type:	Journal Article
Publication:	International Journal of Biological Macromolecules
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Carbohydrates;conformation;protein-carbohydrate interaction; computer modelling technique;concanavalin A;trimannosidic core.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	03 Sep 2009 09:55
Last Modified:	19 Sep 2010 05:43
URI:	http://eprints.iisc.ac.in/id/eprint/22685

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