Abstract:In this paper, Black bean nattokinase crude extract (BNCE) was isolated by fermenting natto from Huguan black beans. Its structural was preliminary investigated, as well as the determination of enzyme activity, thrombolytic function and immunomodulatory effect were carried out. The structure of BNCE is identified by infrared spectroscopy and scanning electron microscopy. Enzymatic activity and thrombolytic function of BNCE were determined by fibrin plate method and animal blood clot method, respectively. The effect of BNCE on the proliferation of RAW264.7 cells was investigated by MTT colorimetric method. Neutral red staining was employed to investigate the effect of BNCE on the phagocytosis rate of RAW264.7 cells. In the effect of BNCE, the secretion of IL-6, TNF-α and IL-1β by RAW264.7 cells was investigated by ELISA. The results showed that BNCE was a protein with different sizes and irregular shapes of fragments, exhibiting certain fibrinolytic activity and thrombolytic function. BNCE can promote the proliferation and enhanced the phagocytosis rate of RAW264.7 cells in normal state as well as in the LPS-activated state in a concentration-dependent manner. In addition, BNCE can also promote the secretion of TNF-α and IL-1β and inhibite the secretion of IL-6 in normal state RAW264.7 cells. Meanwhile, BNCE can also inhibite the secretion of IL-6, TNF-α and IL-1β in LPS-activated state RAW264.7 cells. Therefore, BNCE has certain immunomodulatory effects, and can be used as a good raw material for food industry.