Purification and Characterization of a Fibrinolytic Enzyme form Bacillus sp. KDO-13 Isolated from Soybean Paste

A microorganism producing fibrinolytic enzyme was isolated from Korean traditional soybean paste and identified as Bacillus sp. KDO-13. The fibrinolytic enzyme was purified to homogeneity by ammonium sulfate fractionation, ion-exchange chromatography on DEAE-celluose, and gel chromatography on Sephadex G-100 of the culture supernatant of Bacillus sp. KDO-13. The molecular weight of the purified enzyme was estimated to be 44,000 by SDS-PAGE. The optimum pH and temperature for the enzyme activity were pH 8.0 and $50{\circ}C$, respectively. The enzyme activity was relatively stable at pH 7.0-9.0 and temperature below $50{\circ}C$. the activity of the enzyme was inhibited by $AI^{3+}$ and $Hg^{2+}$, but activated by $Co^{2+}$\;and\;Ni^{2+}. In addition, the enzyme activity was potently inhibited by EDTA and 0-phenanthroline. The purified enzyme could completely hydrolyze a fibrin substrate within 6 h in vitro, and had a low $K_m$ value for fibrin hydrolysis. It was concluded that the purified enzyme was a metalloprotease with relatively high specificity for fibrinolysis, and thus, could be applied as an effective thrombolytic agent.