Determination and properties of the fibrinolysis accelerating substance (FAS) in Japanese fermented soybean "Natto"

Abstract

Using trypsin-fibrin plate method, strong activity of the fibrinolysis accelerating substance (FAS) was proved in water extract of Japanese fermented soybean "natto". In 7 commercial natto preparations, high concentrations of 74,100±54,500 units (equivalent to μg surfactin)/100 g wet weight (Mean±SD) were detected. FAS strongly accelerated not only the activities of direct fibrin degradating enzymes such as plasmin, trypsin, and earthworm protease, but also that of the plasminogen activator (urokinase) and pro-urokinase activator (nattokinase). It was easily separated as dark yellow powder from natto extract by two-step procedures of acid-precipitation (pH 2.0) and ethanol treatment (soluble fraction). The final yield and purity from 1 kg natto were about 817,000 units (dry weight 4.6 g) and 177.6 units/mg, respectively.