Biological properties of kinin-releasing enzyme from Trimeresurus okinavensis (himehabu) venom.

A kinin-releasing enzyme was isolated and characterized from the venom of Trimeresurus okinavensis (himehabu) using Sephadex G-100, DEAE-Cellulose, and CM-Cellulose column chromatographies. The kinin-releasing enzyme was homogeneous as demonstrated by a single band on polyacrylamide gel electrophoresis, and isoelectric focusing. The enzyme possesses a molecular weight of 31,000 Da and isoelectric point of 8.2 and consists of 312 total amino acid residues. Specific esterolytic activities of the kinin-releasing enzyme on N-tosyl-L-arginine methyl ester (TAME) and N-benzoyl-L-arginine ethylester (BAEE) were determined to be 235.3 and 111.3 mumol/min/mg, respectively. The enzyme was inhibited by p-APMSF (p-amidinophenylmethanesulfonyl fluoride hydrochloride) and benzamidine. Additionally, the enzyme was found stable to heat treatment. The enzyme cleaved a kininogen analog with the release of bradykinin, resulting in an immediate drop in blood pressure, and contractions of the rat uterus were also observed.