Abstract:

Abstract:Objective To discuss the optimum temperature and optimum pH of Neanthes japonica (Iznka) fibrinolytic enzyme (NJF) and detect the effects of metal cations and protease inhibitors on the proteolytic activities of NJF and confirm the enzymological classification of NJF. Methods The optimum temperature and pH of NJF were measured by using azocasein as a substrate. The enzyme activities of NJF were determined through ten metal cations (Na^+,K⁺,Cu²⁺,Ca²⁺,Zn²⁺,Co²⁺,Fe²⁺,Fe³⁺,Al³⁺,and Hg²⁺) by using azocasein as a substrate. The enzymological classification of NJF was analyzed by nine protease inhibitors (PMSF,EDTA,EGTA,β-mercaptoethanol,benzamidine,indoaceticacid,aprotinin,pepstatin and soybean trypsin inhibitor). Results NJF had wide thermal stability and pH stability. The enzyme activity was stable between 40℃ and 80℃,and in the pHrange of 7-11. The optimum temperature was 40℃ and the optimum pH was 9.0. The enzyme activity was inhibited completely by Hg ²⁺,and inhibited slightly by Cu²⁺. The other metal cations mentioned above had no obvious effects on the enzyme activity. The enzyme activity was completely inhibited by a typical serine protease inhibitor PMSF. Conclusion NJF is a typical serine protease.

Key words: Neanthes japonica (Iznka);enzyme properties;serine protease;optimum pH;optimum temperature