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Carbohydrate Specificity and Salt-bridge Mediated Conformational Change in Acidic Winged Bean Agglutinin

Manoj, N and Srinivas, VR and Surolia, A and Vijayan, M and Suguna, K (2000) Carbohydrate Specificity and Salt-bridge Mediated Conformational Change in Acidic Winged Bean Agglutinin. In: Journal of Molecular Biology, 302 (5). pp. 1129-1137.


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Structures of two crystal forms of the dimeric acidic winged bean agglutinin (WBAII) complexed with methyl-a-D-galactose have been determined at 3.0 A and 3.3 A resolution. The subunit structure and dimerisation of the lectin are similar to those of the basic lectin from winged bean (WBAI) and the lectin from Erythrina corallodendron (EcorL). The conformation of a loop and its orientation with respect to the rest of the molecule in WBAII are, however, different from those in all the other legume lectins of known structure. This difference appears to have been caused by the formation of two strategically placed salt bridges in the former. Modelling based on the crystal structures provides a rationale for the specificity of the lectin, which is very different from that of WBAI, for the H-antigenic determinant responsible for O blood group reactivity. It also leads to a qualitative explanation for the thermodynamic data on sugar-binding to the lectin, with special emphasis on the role of a tyrosyl residue in the variable loop in the sugar-binding region in generating the carbohydrate specificity of WBAII.

Item Type: Journal Article
Publication: Journal of Molecular Biology
Publisher: Academic Press
Additional Information: The copyright belongs to Academic Press
Keywords: legume lectin;protein crystallography;protein carbohydrate interactions;carbohydrate binding;H antigenic specificity
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 02 Sep 2004
Last Modified: 19 Sep 2010 04:14
URI: http://eprints.iisc.ac.in/id/eprint/1381

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