Purification and characterization of a thrombin like enzyme, elegaxobin II, with lys-bradykinin releasing activity from the venom of Trimeresurus elegans (Sakishima-Habu).

A thrombin like enzyme, named elegaxobin II, with Lys-bradykinin releasing activity was purified from the venom of Trimeresurus elegans (Sakishima-habu) by gel-filtration on Sephadex G-100, and ion-exchange chromatography on the Q-Sepharose Fast Flow. By this procedure, about 9mg of purified enzyme was obtained from 1.1g of the venom. The purified enzyme showed a single protein band, the molecular weight of which was estimated to be about 35,000Da by sodium dodecyl sulfate-PAGE) under reducing condition, and this enzyme was found to contain a carbohydrate moiety. The specific activity of this enzyme toward tosyl-L-arginine methyl ester (TAME) was 250 TAME units/mg of protein. This enzyme clotted only rabbit fibrinogen, whereas human and bovine fibrinogens were unaffected. In the fibrinogen-fibrin conversion, this enzyme released only fibrinopeptide A from rabbit fibrinogen, whereas it did not release fibrinopeptide B. Furthermore, elegaxobin II released Lys-bradykinin when the enzyme was incubated with bovine plasma. The esterase activity was inhibited by p-amidinophenylmethanesulfonyl fluoride hydrochloride (p-APMSF), suggesting that this enzyme is a serine protease. The N-terminal sequence (Val-Ile-Gly-Gly) of this enzyme was identical to the typical sequence of serine proteinases.