ISOLATION AND CHARACTERIZATION OF CAJANUS-CAJAN LECTIN

Cajanus cajan lectin was isolated by ammonium sulfate fractionation an d affinity chromatography on an IgM-Sepharose 6B column. Gel filtratio n and SDS-PAGE showed size homogeneity of the lectin. The lectin with M(r) 18,000 on SDS-PAGE had gel filtration behavior which was consiste nt with a molecular weight of 39 kDa and a Stokes radius of 2.74 nm. T he results showed that the lectin is a dimer composed of identical sub units with N- and C-terminal residues of threonine and alanine, respec tively. The glycoprotein lectin contained 3% concanavalin A-reactive n eutral carbohydrates. Its amino acid composition is characterized by h igh contents of acidic amino acids. The number of tyrosine and tryptop han residues per mole of the lectin was determined to be 14 and 4, res pectively, by spectrophotometry. Results on the effects of large numbe rs of saccharides on lectin-mediated hemagglutination and lectin-IgM p recipitation showed that the C. cajan lectin was specific for mannose and glucose. A comparative study of the properties of C. cajan lectin and concanavalin also presented. (C) 1995 Academic Press, Inc.