The action of trypsin and chymotrypsin on the reserve proteins of some leguminous seeds

Abstract

The action of trypsin on the reserve proteins of the leguminous seeds belonging to Vicieae and Phaseoleae tribes was investigated. The hydrolysis of 11S and 7S proteins of Vicieae proceeds relatively fast and some of the proteins are hydrolyzed practically completely. The hydrolysis of most of the investigated reserve proteins of the Phaseoleae tribe proceeds much slower, while that of 7S proteins of four Phaseolus species of American origin stops after the cleavage of only 10–20% of peptide bonds capable of reacting. Analogous results were obtained studying the action of chymotrypsin on a more restricted number of proteins. Both trypsin and chymotrypsin hydrolyze the same parts of Ph. vulgaris 7S protein, splitting off peptides which can be separated on a Sephadex G-50 column. The nonhydrolyzable high molecular weight core has a slightly smaller sedimentation coefficient and a higher electrophoretic mobility than the native protein and is able to dimerize at high ionic strength. Urea does not alter the hydrolyzability of the core butt the latter is partially hydrolyzed after the action of urea or guanidine hydro-chloride in the presence of mercaptoethanol.