The immunological and physicochemical properties of mitogenic proteins derived from Phaseolus vulgaris.

A commercially available phytohaemagglutinin derived from (PHAP) was subjected to CM Sephadex and Sephadex G-150 chromatography. Two major mitogenic fractions were isolated; one (L-PHAP), appeared homogeneous by polyacrylamide gel electrophoresis, and was virtually lacking in haemagglutinating activity, while the other (H-PHAP) was a potent haemagglutinin. H-PHAP was a complex material as shown by its behaviour on CM Sephadex chromatography. Electrophoretic analysis revealed three distinct bands of protein, all migrating cathodally to L-PHAP. With increasing cathodal mobility H-PHAP subfractions showed diminishing mitogenicity, increasing haemagglutinating potency, and the appearance of the ability to precipitate serum proteins non-specifically. The latter property, present in crude PHAP, was not displayed by L-PHAP. The mitogenic activity of all H-PHAP subfractions was potentiated by the presence of autologous red blood cells. While L- and H-PHAP were closely related by immunological criteria, distinct differences were noted by three methods of analysis. The most cathodal of the H-PHAP subfractions was found to be immunodeficient by comparison with crude PHAP, L-PHAP, and the remaining H-PHAP subfractions. The implications of these findings with respect to the biological activity of PHAP and to its subunit structure are discussed.