The Structure of Legumin ofVicia fabaL.—a Reappraisal

Abstract

Two-dimensional electrophoretic studies have shown a wide range of heterogeneity in the subunits of legumin isolated from seeds of Vicia faba L. As many as 10 disulphide-linked subunit pairs in the mol. wt. range 37 000–79 000 have been observed. Each subunit pair separated on reduction by 2-mercaptoethanol into a large acidic and a small basic subunit, each of which was shown to be heterogeneous in charge by isoelectric focusing. More heterogeneity was found in the large subunits (mol. wt. range 23 000–58 000; pl range 4.6–6.1) than in the small subunits (mol. wt. range 21 000–23 000; pl range 8.2–8.5). Most legumin molecules seemed to be formed by random association of subunit pairs, although one subunit pair associated only with itself to give a molecular type separable under non-dissociating conditions.