Thermodynamics of Monosaccharide and Disaccharide Binding to Erythrina corallodendron Lectin

Surolia, Avadhesha and Sharon, Nathan and Schwarz, Frederick P (1996) Thermodynamics of Monosaccharide and Disaccharide Binding to Erythrina corallodendron Lectin. In: Journal of Biological Chemistry, 271 (30). 17697 -17703.

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Abstract

Isothermal titration calorimetry measurements of the binding of 2′-fucosyllactose, lactose, N-acetyllactosamine, galactopyranose, 2-acetamido-2-deoxygalactopyranoside, methyl α-N-dansylgalactosaminide (Me-α-DNS-GalN), methyl α-D-galactopyranoside, methyl β-D-galactopyranoside, and fucose to Erythrina corallodendron lectin (ECorL), a dimer with one binding site per subunit, were performed at 283-286 and 297-299 K. The site binding enthalpies, ΔHb, with the exception of Me-α-DNS-GalN, are the same at both temperatures and range from −47.1 ± 1.0 kJ mol−1 for N-acetyllactosamine to −4.4 ± 0.3 kJ mol−1 for fucose, and the site binding constants range from 3.82 ± 0.9 × 105 M−1 for Me-α-DNS-GalN at 283.2 K to 0.46 ± 0.05 × 103 M−1 for fucose at 297.2 K. The binding reactions are mainly enthalpically driven except for fucose and exhibit enthalpy-entropy compensation. The binding enthalpies of the disaccharides are about twice the binding enthalpies of the monosaccharides in contrast to concanavalin A where the binding enthalpies do not double for the disaccharides. Differential scanning calorimetry measurements show that denaturation of the ECorL dimer results in dissociation into its monomer subunits. The binding constants from the increase in denaturation temperature of ECorL in the presence of saccharides are in agreement with values from isothermal titration calorimetry results. The thermal denaturation of ECorL occurs around 333 K, well below the 344-360 K denaturation temperature of other legume lectins of similar size and tertiary structure, undoubtedly due to the difference in its quaternary structure relative to other legume lectins. This is also apparent from the independent unfolding of its two domains.

Item Type:	Journal Article
Publication:	Journal of Biological Chemistry
Publisher:	The American Society for Biochemistry and Molecular Biology
Additional Information:	Copyright of this article belongs to The American Society for Biochemistry and Molecular Biology.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	22 Jan 2010 05:14
Last Modified:	19 Sep 2010 05:51
URI:	http://eprints.iisc.ac.in/id/eprint/24747

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