Abstract:[Objective] Thrombolytic therapy is a safe and effective treatment for thrombotic diseases. Microorganisms are possible sources of thrombolytic drugs. We purified and characterized fibrinolytic enzyme produced by Bacillus subtilis strain BS-26. [Methods] We examined the fibrinolytic enzyme activity by fibrin plate and purified fibrinolytic enzyme by ammonium sulfate fractional precipitation, anion-exchange chromatography on DEAE-Sepharose Fast Flow and prepara-tive PAGE. [Results]The fibrinolytic enzyme of the strain BS-26 was stable blow 50℃ and pH5.0-11.0, the optimal temperature was 42℃ and optimal pH was 9.0. Ca2+ and Mg2+ ions enhanced the fibrinolytic activity, whereas Cu2+ com-pletely inhibited the enzyme. Phenylmethylsulfonyl fluoride (174.2 mg/mL), chicken ovomucoid (1000 mg/mL) and soy-bean trypsin inhibitor (1000 mg/mL) could inhibit enzyme activity, which indicated that the enzyme belonged to serine protease group. On plasminogen-free fibrin plates and plasminogen fibrin plates, the fibrinolytic activity had no obvious difference, indicating that the enzyme was a fibrinolytic enzyme which degraded fibrin directly, but not a plasminogen activator which degraded fibrin by activating plasminogen. A fibrinolytic enzyme was purified from the fermentation broth with recovery yield of 3.2%, purification factor of 41.0 fold and the specific activity 8750.0 U/mg. SDS-PAGE analysis of the purified protein showed only one band with molecular mass of 32 kDa. [Conclusion]A single fibrinolytic enzyme was purified, which provided the basis for large-scale production of fibrinolytic enzyme.
