Action of the Kallikreins on Synthetic Ester Substrates

Summary Evidence is presented which suggests that the kallikreins derived from hog pancreas, human pancreas, human urine and human plasma are capable of digesting those synthetic esters which contain arginine as the specific amino acid residue. Highly purified hog pancreatic kallikrein also digests acetyl-L-tyrosine ethyl ester. Arginine esters and benzoyl-L-arginine amide prevented both inhibition of human urinary and pancreatic kallikreins by human plasma and inhibition of human plasma kallikrein by diisopropyl-fluorophosphate. Acetone activates not only plasma kallikrein but another proteolytic enzyme(s) which attack arginine esters and are not inhibited by SBTI.