Identification And Characterization Of Marine Actinomycetes Strains Producing Fibrinolytic Enzyme

The fibrinolytic enzyme is an important part of the fibrinolytic system.It can specificly degrade fibrin coagulation pieces.Fibrinolytic therapy is available,which has been widely used in clinical practice.However,the current thrombolytic drugs have some side effects,it is great importance of developing a new type of thrombolytic agent with few side effects.As marine actinomycetes grow in the particular marine environment,they possess unique physiological characteristics and metabolic pathways.Therefore,they become the important new sources to screen novel active fibrinolytic enzyme from marine actinomycetes.A fibrinolytic enzyme producing actinomycetes strain,named MY0504,was screened out from the mud and sea water samples collected in the Bohai Sea,using conventional separation screening methods.The actinomycetes strain was identified as Streptomyces albidoflavus by morphological identification,physiological and biochemical characteristics and 16S rDNA sequence ana1ysis.The strain and the fermentation broth were safe and non-toxic.The fibrinolytic enzyme was purifid from the fermentation broth as following procedures:high-speed centrifugation,40⁶0%ammonium sulfate precipitation,dialysis,lyophilization and Sephadex G-75 gel filtration.The purified fibrinolytic enzyme exhibited a single peak in SDS-PAGE electrophoresis.It was purified with a purification fold of 7.15and a yield of 32%.The molecular weight of the enzyme was about 14¹5 kD.Through the study on the enzymatic properties of fibrinolytic enzyme,we came to the following conclusions:The optimum temperature and pH of fibrinolytic enzyme was 37?and 8.0,while it had good stability below 47?and kept activity with the suitable pH in the range of 7⁹.It was a partial alkaline protease.The fibrinolytic activity was strongly inhibited by Cu²⁺,while was promoted little by Ca²⁺.Aprotinin strongly inhibited the fibrinolytic activity and PMSF?phenylmethylsulfonyl fluoride?can completely inhibit it.It was initially speculated that the fibrinolytic enzyme is one kind of serine protease.