Production, Purification and Characterisation of a Potential Fibrinolytic Protease from Endophytic Xylaria curta by Solid Substrate Fermentation

The present investigation highlights the optimal conditions for production of a non-toxic, bi-functional fibrinolytic enzyme xylarinase produced by endophytic fungus Xylaria curta by solid substrate fermentation using rice chaff medium. The purified enzyme is a monomeric protein with a molecular mass of ∼33 kDa. The enzyme exhibits cleavage of Aα and Bβ chains of fibrin(ogen) and has no effect on γ chain. The optimal fibrinolytic activity of the enzyme was observed at 35 °C and pH 8. The fibrinolytic activity was enhanced in the presence of Ca 2+ , whereas it was completely inhibited in the presence of Fe 2+ and Zn 2+ ions and inhibitors like EDTA and EGTA suggesting it to be a metalloprotease. The K m and V max of the enzyme for azocasein were 326 μM and 0.13 μM min −1 . The N-terminal sequence of the enzyme (SNGPLPGGVVWAG) was same when compared to xylarinase isolated from culture broth of X. curta . Thus, xylarinase could be exploited as a potent clot busting enzyme which could be produced on large scale using solid substrate fermentation.