Kinin-releasing enzyme from the venom of Bitis arietans (puff adder).

A kinin-releasing enzyme was isolated from Bitis arietans (puff adder) venom by Sephadex G-100 and DEAE-cellulose column chromatographies. The kinin-releasing enzyme was shown to be homogeneous as demonstrated by a single band on acrylamide gel electrophoresis, isoelectric focusing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunodiffusion. Its molecular mass is approximately 45 kDa with an isoelectric point of 6.5. Kinin-releasing enzyme possesses proteolytic activity which hydrolyzes the Leu6-Cys7, His10-Leu11 and Ala14-Leu15 bonds of the B chain of oxidized insulin and the A alpha and B beta chain of fibrinogen. Kinin-releasing and benzoyl-L-arginine ethyl ester hydrolytic activities of this enzyme were inhibited by diisopropyl fluorophosphate, suggesting that the serine hydroxyl group is involved in enzymatic activities.