Separation and biological properties of Phaseolus vulgaris isolectins

Two isolectins (L4E0-PHA and L0E4-PHA) from red kidney beans (Phaseolus vulgaris) were isolated by affinity chromatography on immobilized thyroglobulin and by chromatography on hydroxyapatite. The L4E0-PHA isolectin was not retarded on the affinity column and was eluted from the hydroxyapatite column with a 0.1 M Phosphate buffer. This isolectin had no erythroagglutinating activity but had high lymphoagglutinating and lymphocyte stimulating activities. The L0E4-PHA isolectin was adsorbed on the affinity column and was eluted from the hydroxyapatite column with a 0.25 M Phosphate buffer. This isolectin has a higo lymphocyte stimulating activity. These two isolectins are shown however to be closely related with respect to their oligomeric structure and reactivity towards anti-PHA antibodies. The lack of mitogenic activity of the L0E4-PHA isolectin suggests that in the other isolectins, the E monomer is not responsible for their mitogenic activity and that the membrane glycoproteins, which contain the E monomer - specific oligosaccharide, are not involved in the process inducing mitosis.