Research Progress on Douchi Fibrinolytic Enzyme

In recent years, the morbidity and mortality owing to thrombotic diseases have increased. Fibrinolytic enzymes can dissolve thrombosis. Existing thrombolytic drugs are expensive, have short half-lives, and cause bleeding easily. Consequently, there is a need to develop safe, effective, and inexpensive thrombolytic drugs. The Douchi fibrinolytic enzyme (DFE), a serine protease that can dissolve fibrous proteins from the traditional fermented food Douchi, has been isolated recently. DFE is non-toxic and free from side effects like bleeding. In addition, it has a low molecular weight, owing to which it can be absorbed directly through the digestive tract or taken orally, thereby attracting increasing attention. In this review, first, we introduce the commonly used methods for determining DFE activity. Second, we summarize the strains of DFE-producing bacteria, optimization of the fermentation process, mutation breeding, and recombinant expression. Finally, we discuss the isolation and purification procedures, physicochemical properties, and in vitro and in vivo thrombolytic effects of DFE. Thus, we demonstrate that the extraction of DFE from Douchi, a traditional Chinese fermented food, has considerable potential for development.