Dipeptidyl-dipeptidase (EC 3.4.14.6, dipeptidyl tetrapeptide hydrolase, dipeptidyl ligase, tetrapeptide dipeptidase) is an enzyme. This enzyme catalyses the following chemical reaction Dipeptidyl-dipeptidase (EC 3.4.14.6, dipeptidyl tetrapeptide hydrolase, dipeptidyl ligase, tetrapeptide dipeptidase) is an enzyme. This enzyme catalyses the following chemical reaction This thiol-activated peptidase is isolated from cabbage (Brassica oleracea).