Endopeptidase activity in jackbeans and its effect on Concanavalin A

Endopeptidase activity in mature jackbeans has been characterised. One major activity is present, that of a neutral metallo-endopeptidase. Using specific inhibitors it can be shown that the Concanavalin A-associated fragments are not formed by proteolytic degradation of the intact subunit on hydration of the tissue. The intact subunit of the lectin is also resistant to the degradation by the endogenous endopeptidase activity during a prolonged incubation in vitro. These results suggest that the lectin fragments have been formed during seed maturation and no further limited proteolysis of Concanavalin A occurs during the early stages of germination.