Similarity between a Kininogenase (Kallikrein) from Human Large Intestine and Human Urinary Kallikrein

Abstract

A human colon kininogenase (kallikrein) was isolated by gel filtration on Sephacryl S-200 and affinity chromatography on Trasylol-bound Sepharose, yielding a material with a specific activity of 1.3 U[units]/mg (substrate: AcPheArg-OEt, N.alpha.-acetyl-L-Phe-L-Arg ethyl ester). The MW of the enzyme as estimated by gel filtration is approximately 70,000. After reduction with mercaptoethanol 2 bands were obtained in dodecyl sulfate electrophoresis with MW of 27,000 and 70,000. The bimolecular velocity constant for the inhibition by diisopropyl fluorophosphate was determined as 4/mol per min. The preparation was characterized by immunological and enzymatic methods. Using the radioimmunoassay for human urinary kallikrein cross-reactivity and parallel binding curves were obtained. Kinin liberation from human high MW-kininogen was totally inhibited by antibodies directed against human urinary kallikrein, Trasylol and diisopropyl fluorophosphate, but not by antibodies directed against human trypsin and plasma kallikrein. The effect on dog blood pressure was comparable to that obtained with human urinary kallikrein. The amino acid composition of human large intestine kallikrein is very similar to that of the human urinary kallikrein.