# Structural basis for the carbohydrate-specificity of basic winged-bean lectin and its differential affinity for Gal and GalNAc

Kulkarni, Kiran A and Katiyar, Samiksha and Surolia, Avadhesha and Vijayan, Mamannamana and Suguna, Kaza (2006) Structural basis for the carbohydrate-specificity of basic winged-bean lectin and its differential affinity for Gal and GalNAc. In: Acta Crystallographica Section-D: Biological Crystallography, 62 (11). pp. 1319-1324.

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## Abstract

The crystal structure of the complexes of basic winged-bean lectin with galactose, 2-methoxygalactose, N- acetylgalactosamine and methyl-\alpha-N-acetylgalactosamine have been determined. Lectin–sugar interactions involve four hydrogen bonds and a stacking interaction in all of the complexes. In addition, an $N-H^{...}O$ hydrogen bond involving the hydroxyl group at C2 exists in the galactose and 2-methoxygalactose complexes. An additional hydrophobic interaction involving the methyl group in the latter leads to the higher affinity of the methyl derivative. In the lectin–N-acetylgalactosamine complex the $N-H^{...}O$ hydrogen bond is lost, but a compensatory hydrogen bond is formed involving the O atom of the acetamido group. In addition, the $CH_3$ moiety of the acetamido group is involved in hydrophobic interactions. Consequently, the 2-methyl and acetamido derivatives of galactose have nearly the same affinity for the lectin. The methyl group \alpha-linked to the galactose takes part in additional hydrophobic interactions. Therefore, methyl-\alpha-N-acetylgalactosamine has a higher affinity than N-acetylgalactosamine for the lectin. The structures of basic winged-bean lectin–sugar complexes provide a framework for examining the relative affinity of galactose and galactosamine for the lectins that bind to them. The complexes also lead to a structural explanation for the blood-group specificity of basic winged-bean lectin.

Item Type: Journal Article Copyright of this article belongs to International Union of Crystallography. Division of Biological Sciences > Molecular Biophysics Unit 08 Jan 2007 19 Sep 2010 04:32 http://eprints.iisc.ernet.in/id/eprint/9046