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Role of water in the specific binding of mannose and mannooligosaccharides to concanavalin A

Swaminathan, Chittoor P and Surolia, Namita and Surolia, Avadhesha (1998) Role of water in the specific binding of mannose and mannooligosaccharides to concanavalin A. In: Journal of the American Chemical Society, 120 (21). pp. 5153-5159.

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We report here, the first solution state evidence for the role of water molecules in the specific interaction of carbohydrates with a legume lectin, concanavalin A. Concanavalin A from Canavalia ensiformis is a protein containing 237 amino acid residues with each monomer possessing one sugar binding site as well as sites for transition-metal ions, Mn2+ and Ca2+. The lectin binds specifically to alpha-anomers of monosaccharides, D-glucopyranoside and D-mannopyranoside, and recognizes the trimannosidic core of N-linked glycoproteins, 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside with high specificity, which constitutes the minimum carbohydrate epitope that completely fills the sugar binding site. Sensitive isothermal titration microcalorimetry coupled with osmotic stress strategy on concanavalin A was used to dissect out the differential involvement of water molecules in the recognition of the branched trimannoside (3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside), the individual dimannosidic arms (3-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside and 6-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside) as well as the monomer unit, D-mannopyranoside, The specific binding of concanavalin A to different sugars, is accompanied by differential uptake of water molecules during the binding process. These results not only complement the X-ray crystallographic studies of legume lectin-sugar complexes displaying structurally conserved water molecules mediating the specific ligation of the sugars with the corresponding sites in the binding pocket but also provide a rationale for the observed compensatory behavior of enthalpies with entropies in lectin-sugar interactions.

Item Type: Journal Article
Publication: Journal of the American Chemical Society
Publisher: American Chemical Society
Additional Information: Copyright of this article belongs to American Chemical Society.
Keywords: Enthalpy-entropy compensation;blood-group determinant;molecular recognition;ulex-europaeus; protein;lectin; thermodynamics;crystal;monosaccharide; energetics.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 01 Dec 2009 09:41
Last Modified: 19 Sep 2010 05:27
URI: http://eprints.iisc.ac.in/id/eprint/19155

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