Fluorescence-polarization studies on binding of 4-methylumbelliferyl beta-D-galactopyranoside to Ricinus communis (castor-bean) agglutinin

Khan, MI and Mathew, MK and Balaram, P and Surolia, A (1980) Fluorescence-polarization studies on binding of 4-methylumbelliferyl beta-D-galactopyranoside to Ricinus communis (castor-bean) agglutinin. In: Biochemical Journal, 191 (2). pp. 395-400.

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Abstract

The binding of Ricinus communis (castor-bean) agglutinin 1 to saccharides was studied by equilibrium dialysis and fluorescence polarization by using the fluorescently labelled sugar 4-methylumbelliferyl beta-D-galactopyranoside. No appreciable change in ligand fluorescence of 4-methylumbelliferyl beta-D-galactopyranoside was considerably polarized on its binding to the lectin. The association constants obtained by Scatchard analysis of equilibrium-dialysis and fluorescence-polarization data do not differ much from each other, and at 25 degrees C, Ka = 2.4 (+/- 0.2) X 10(4)M-1. These values agree reasonably well with that reported in the literature for Ricinus agglutinin 1. The number of binding sites obtained by the different experimental procedures is 1.94 +/- 0.1 per molecule of 120 000 daltons and is equal to the reported value of 2. The consistency in the values of Ka and number of binding sites indicate the absence of additional subsites on Ricinus agglutinin 1 for its specific sugars. In addition, the excellent agreement between the binding parameters obtained by equilibrium dialysis and fluorescence polarization indicate the potential of ligand-fluorescence-polarization measurements in the investigation of lectin-sugar interactions.

Item Type:	Journal Article
Publication:	Biochemical Journal
Publisher:	Portland Press
Additional Information:	Copyright of this article belongs to the Portland Press.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	21 Jul 2009 14:32
Last Modified:	19 Sep 2010 05:32
URI:	http://eprints.iisc.ac.in/id/eprint/20283

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