Isolation of the acidic and basic lectins from winged bean seed ( Psophocarpus tetragonolobus (L.) DC)

Abstract The acidic and basic lectins of the winged bean were isolated from seed extracts by affinity chromatography on lactose‐Sepharose 6B and melibiose Bio‐Gel P150, respectively. The lectins isolated from six varieties of Psophocarpus tetragonolobus , collected from different regions of south‐east Asia, showed no significant differences in their properties; their subunit M r and amino acid compositions were the same as those of the acidic and basic lectins isolated by non‐affinity methods. On isoelectric focusing the affinity purified acidic lectins showed two major protein components (isolectins) while the affinity purified basic lectins had four protein components. The acidic lectins showed a preference for β‐D‐galactosides and they agglutinated trypsinised human type A, B and O erythrocytes but not trypsinised rabbit erythrocytes. The basic lectins showed a preference for α‐D‐galactosides and they agglutinated trypsinised rabbit and human type A and B erythrocytes but not trypsinised human type O erythrocytes.