Herinase: A Novel Bi-functional Fibrinolytic Protease from the Monkey Head Mushroom, Hericium erinaceum

Herinase, a new bi-functional fibrinolytic metalloprotease, was purified from a medicinal and edible mushroom Hericium erinaceum. The enzyme was monomeric with a molecular mass of 51 kDa. Analysis of fibrin zymography showed an active band with a similar molecular mass. The N-terminal sequence of herinase VPSSFRTTITDAQLRG was highly distinguished from known fibrinolytic enzymes. Moreover, the enzyme activity was strongly inhibited by EDTA and EGTA, indicating that herinase is a metalloprotease. Herinase exhibited high specificity for the substrate t-PA followed by plasmin. The K (m) and V (max) values for H-D-Ile-Pro-Arg-PNA were found to be 4.7 mg and 26.7 U/ml respectively. Similarly, fibrin plate assays revealed that it was able to degrade fibrin clot directly and also able to activate plasminogen. Herinase provoked a rapid degradation of fibrin and fibrinogen alpha chains and slower degradation of gamma chains. It had no activity on the beta chains of fibrin and fibrinogen. This result suggests that herinase could possibly contain higher amount of alpha-fibrinogenase. The activity of herinase was stimulated by metal ions such as Ca2+, Mg2+, and Mn2+, but inhibited by Cu2+, Fe2+, and Zn2+. Herinase exhibited maximum activity at 30 A degrees C and pH 7.0. These results demonstrate that herinase could be a novel fibrinolytic enzyme.