Partial purification and characterization of two Peptide hydrolases from pea seeds

Two peptide hydrolases have been found in pea seeds (Pisum sativum var. Greenfeast) and extensively purified by ion exchange chromatography using benzoyl-dl-arginine-p-nitroanilide as substrate. The enzymes which both have molecular weights of 65,000 can be separated by anion exchange chromatography but are otherwise virtually identical in the properties tested. They did not hydrolyze several common protease substrates but readily hydrolyzed small peptides containing basic amino acids on the carboxyl side of these residues. They are completely inhibited by diisopropylfluorophosphate and are inhibited to varying extents by thiol reagents.