A Study on Fibrinolytic Activity of Nattokinase from Natto

The fibrinolytic Properties of nattokinase was studied by preparing saline extract of natto and crude enzyme of nattokinase, and the results showed nattokinase was stable within pH 6～10 and below 40℃, its optimum pH was 8, but inactivated completely below pH 5. Under simulating acid environment of stomach, the fibrinolytic activity of crude extract of nattokinase lost completely while 25% of the fibrinolytic activity of saline extract of natto retained. The SDS-PAGE results showed nattokinase can not be hydrolyzed by trypsin; nattokinase can hydrolyze fibrin directly rather than by activating plasminogen in vitro.