Actions of two serine proteases from Trimeresurus jerdonii venom on chromogenic substrates and fibrinogen.

Jerdonobin and jerdofibrase are two serine proteases purified from the venom of Trimeresurus jerdonii. The Michaelis constant K(m) and the catalytic rate constant K(cat) of jerdonobin or jerdofibrase on three chromogenic substrates, H-D-Pro-Phe-Arg-pNA (S2302), H-D-Phe-pipecolyl-Arg-pNA (S2238), and H-D-Val-Leu-Lys-pNA (S2251) were obtained from lineweaver-Burk plots. Jerdofibrase could hydrolyze all three substrates, but jerdonobin had no detectable activity on S2251, suggesting a relatively broader substrate specificity for jerdofibrase than jerdonobin. By SDS-PAGE, jerdofibrase preferentially degraded Bbeta-chain of fibrinogen. It also degraded Aalpha-chain of fibrinogen with relatively slow activity, but did not act on the gamma-chain. In contrast, jerdonobin did not degrade fibrinogen within 12 h. Fibrinopeptides liberation test, identified by HPLC, showed jerdonobin released fibrinopeptide A and a small amount of fibrinopeptide B. Unlike jerdonobin, jerdofibrase mainly released fibrinopeptide B. These results indicate that the two enzymes differ in their ability to hydrolyze chromogenic substrates and in their actions on fibrinogen.