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Studies on a chitooligosaccharide-specific lectin from Coccinia indica. Thermodynamics and kinetics of umbelliferyl glycoside binding.

Sanadi, AR and Surolia, A (1994) Studies on a chitooligosaccharide-specific lectin from Coccinia indica. Thermodynamics and kinetics of umbelliferyl glycoside binding. In: Journal of Biological Chemistry, 269 (7). pp. 5072-5077.

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Official URL: http://www.jbc.org/content/269/7/5072.abstract

Abstract

Coccinia indica agglutinin (CIA) is a chitooligosaccharide-specific lectin with two binding sites/homodimer of M(r) 32,000. Quenching studies implied tryptophan involvement in binding activity, which was confirmed by chemical modification experiments (A. R. Sanadi and A. Surolia, submitted for publication). Binding of 4-methylumbelliferyl chitooligosaccharides has been carried out to study their binding by CIA. Reversal experiments confirm the validity of the data previously obtained (A. R. Sanadi and A. Surolia, submitted for publication) from intrinsic fluorescence studies. Surprisingly, unlike wheat germ agglutinin, there is no consistent thermodynamic effect of the chromophoric label on binding activities as compared with the native sugars. From the changes in the optical properties of the chromophoric group upon binding to CIA, it has been possible to confirm that the tryptophan located in the binding site is closest to the fourth subsite. Thermodynamic analysis shows that the binding of the labeled tetrasaccharide is very strongly entropically driven, with the terminal, nonreducing sugar residue protruding from the binding pocket. The results of stopped-flow kinetic studies on the binding of the chromophoric trisaccharide by CIA show that the mechanism of binding is a one-step process.

Item Type: Journal Article
Additional Information: Copy right of this article belongs to The American Society for Biochemistry and Molecular Biology.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 04 May 2010 10:07
Last Modified: 19 Sep 2010 06:01
URI: http://eprints.iisc.ernet.in/id/eprint/27506

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