Purification and Characterisation of a Fibrinolytic Enzyme from Rhizopus microsporus var. tuberosus


Shuli Zhang, Yingdong Wang, Nan Zhang, Zhe Sun, Yan Shi, Xingnan Cao and Haikuan Wang*


Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science and Technology, Ministry of Education, Tianjin , PR China



Article history:
Received August 25, 2014
Accepted March 9, 2015



Key words: 
Rhizopus microsporus var. tuberosus, fibrinolytic enzyme, purification, characterisation

Summary:
Extracellular fibrinolytic enzyme from Rhizopus microsporus var. tuberosus was purified and characterised. The microorganism was isolated in a distillery from daqu, a fermentative agent used in the production of Chinese liquor and vinegar at different temperatures. The fibrinolytic enzyme was partially purified by ammonium sulphate precipitation, dialysis, DEAE Sepharose^® Fast Flow ion exchange chromatography and Sephadex G-75 gel filtration chromatography. The molecular mass of the fibrinolytic enzyme was estimated to be 24.5 kDa by SDS-PAGE. The purified enzyme showed optimal activity at pH=7.0 and 37 °C by fibrin plate method. It showed stronger resistance to the inhibition by trypsin and was stable at 37 °C retaining 96.1 % residual activity after 4 h of incubation. The fibrinolytic activity of the enzyme was enhanced by Na⁺, Ca²⁺, Mg²⁺ and Mn²⁺. Conversely, Zn²⁺ and Cu²⁺ partly inhibited enzymatic activity. Using fibrin plate method, we found that the enzyme not only degrades fibrin directly, but also activates plasminogen into plasmin to degrade fibrin. The results indicate that the pure enzyme has a potential in dissolving blood clot, and the possibility for application in the treatment of thrombosis.

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