Characterization of a lectin from the leaves of great northern bean, Phaseolus vulgaris L.

A novel lectin (GN(L)L) was isolated from the leaves of the Great Northern bean, Phaseolus vulgaris. GN(L)L was purified by affinity chromatography on ovomucoid-Sepharose 4B. GN(L)L had a molecular mass of 135 kDa on gel filtration and gave two bands on SDS-polyacrylamide gel electrophoresis (PAGE) (band A of 34.0 kDa and band B of 34.2 kDa). Binding assay of horseradish peroxidase (HRP)-glycoproteins to the bands electroblotted onto polyvinylidene difluoride (PVDF) membrane showed that both bands could bind to complex-type N-linked oligosaccharide chains in glycoproteins. The N-terminal amino acid sequences of both bands were identical through the 10 residues and identical to that of alpha-subunit of a pod lectin (pod-alpha-subunit) from the same bean. On the other hand, band B cross-reacted with monoclonal antibody against a seed lectin from the same bean, but band A did not.