Abstract
Winged bean basic lectin was purified by affinity chromatography on p-aminophenyl-β-Dgalactopyranoside bound Sepharose 4B. The purified lectin was homogeneous on polyacrylamide gel electrophoresis, isoelectric focusing, and gel filtration. The molecular weight of the lectin was 53, 000±1, 800 by gel filtration, SDS-polyacrylamide gel electrophoresis gave a single component of molecular weight of 27, 000, suggesting that the lectin was a dimer. The isoelectric point was pH 8.62±0.17. The basic lectin was rich in aspartic acid and threonine, and poor in sulfur-containing amino acids. The basic lectin agglutinated both trypsinized and untreated human erythrocytes; it bound highest with type A, somewhat lower with types B and AB, and negligibly with type O erythrocytes. Among the tested sugars, D-galactose and N-acetyl-D-galactosamine were active in inhibiting the hemagglutination. In contrast, the determinant sugars in blood group O, such as L-fucose and N, N'-diacetylchitobiose, were entirely inactive, confirming the blood group-specificity of the basic lectin. Modification of the lectin with N-bromosuccinimide led to a significant decrease in its hemagglutinating activity, suggesting contribution of the tryptophan residues to the activity.
