[Modification of vetch seed reserve proteins during germination and limited proteolysis].

The split-off 1-2 short peptides is the first stop in the endogenous protease A effect on the vetch legumin, which results in a step-wise rise of its hydrolyzability by two other endogenous proteases (B and C). Short neutral and basic peptides are consecutively split off from the acid subunits in the course of subsequent hydrolysis by protease A, while the breakdown of these subunits into larger fragments, which are retained in the legumin molecule by non-covalent bonds, occurs later. Similar results were obtained in experiments on trypsin action of legumin. Thus the initial course of legumin hydrolysis is largely determined by its structure. The changes of legumin during germination are similar to those occurring upon limited proteolysis by protease A. However, some differences are indicative of the existence of other factors responsible for the modification of this protein during germination. The modification of vicilin during germination and limited proteolysis occurs apparently in a similar way.