Extracellular fibrinolytic
enzyme from Rhizopus microsporus var. tuberosus was purified and characterised. The microorganism was isolated in a distillery from daqu, a fermentative agent used in the production of Chinese liquor and
vinegar at different temperatures. The fibrinolytic
enzyme was partially purified by
ammonium sulphate precipitation, dialysis,
DEAE Sepharose® Fast Flow ion exchange chromatography and
Sephadex G-75 gel filtration chromatography. The molecular mass of the fibrinolytic
enzyme was estimated to be 24.5 kDa by SDS-PAGE. The purified
enzyme showed optimal activity at pH=7.0 and 37 °C by
fibrin plate method. It showed stronger resistance to the inhibition by
trypsin and was stable at 37 °C retaining 96.1% residual activity after 4 h of incubation. The fibrinolytic activity of the
enzyme was enhanced by Na+, Ca2+, Mg2+ and Mn2+. Conversely, Zn2+ and Cu2+ partly inhibited enzymatic activity. Using
fibrin plate method, we found that the
enzyme not only degrades
fibrin directly, but also activates
plasminogen into
plasmin to degrade
fibrin. The results indicate that the pure
enzyme has a potential in dissolving
blood clot, and the possibility for application in the treatment of
thrombosis.