A potent extracellular fibrinolytic enzyme was obtained from cultures of the imperfect fungus Fusarium semitectum under certain growth conditions. Nitrate addition to cultures increased enzyme production. The enzyme showed a versatile proteolytic activity against several protein substrates including casein, gelatin, haemoglobin, bovine serum albumin, and fibrin from both buffalo and human sources.Optimal fibrinolysis occurred at p H values around 7.0. The fibrinolytic activity exhibited marked heat stability in enzyme samples heated to 60 "C, and retained more than 40% of its activity i n samples heated to 100 "C for 10 min. Fibrinolysis proceeded optimally in the temperature range between 60-60 "C. Copper ions significantly activated the enzyme. Other biochemical properties are also reported.Lately, there has been great interest in the search for new thrombolytic agents from various origins with particular reference to microbial sources. This interest was stimulated by the discovery by TILLETT and GARNER (1933) of a bacterial enzyme capable of thrombus dissolution. Subsequent investigations reviewed by TAYLOR and TOMAR (1970) demonstrated the value of the enzyme, streptokinase, in the therapy of thrombosis in man. GRINBERG and MIKHAILETS (1972) studied a fibrinolytic enzyme, terrilytin, obtained from Aspergillus terricola and demonstrated its effectivity in preventing thrombus forination in vitro. From Yenicillium lilacinurn EGOROV et al. (1972) isolated a strong thrombolytic enzyme which was active against fibrin, haemoglobin, and casein substrates. An active fibrinolytic enzyme formed in submerged cultures of Tnchothecium roseum was reported by ANDREENKO et al. (1973). This enzyme, tricliolysin, was formed by the fungus during the entire growth period and its production was favoured by the presence of high concentrations of carbon compounds and protein substrates in the medium. Recently, FODA and FAYEK (1975) obtained potent fibrinolytic preparations from cultures of Bacillus subtilis.Although several microbial enzymes were shown to possess thrombolytic activities in vitro, for various reasons only one enzyme, namely streptokinase, has thus far, been used in the treatment of thrombosis in man. This necessitates further search for new sources of this vitally important group of enzymes. The present paper reports the production physiology and properties of a promising fibrinolytic activity from the imperfect fungus Fusarium semitectum. Materials and methodsOrganism used and growth conditions: A strain of Fusarium semitectum obtained from the NRC collection was used throughout this study. This fungus was selected based on an initial screening for proteolytic enzyme producers. The medium used for fungal growth contained: glucose lyo, potassium dihydrogen phosphate 0.5%, magnesium sulfate 0.05y0, and traces of ferrous sulfate. Enzyme production: The fungus was grown in 300 ml conical flasks each containing 50 ml aliquots of the liquid medium. These flasks were originally inoculated from an exponentially growing cul...

A potent extracellular fibrinolytic enzyme was obtained from cultures of the imperfect fungus Fusarium semitectum under certain growth conditions. Nitrate addition to cultures increased enzyme production. The enzyme showed a versatile proteolytic activity against several protein substrates including casein, gelatin, haemoglobin, bovine serum albumin, and fibrin from both buffalo and human sources. Optimal fibrinolysis occurred at pH values around 7.0. The fibrinolytic activity exhibited marked heat stability in enzyme samples heated at 60 degrees C, and retained more than 40% of its activity in samples heated to 100 degrees C for 10 min. Fibrinolysis proceeded optimally in the temperature range between 50--60 degrees C. Copper ions significantly activated the enzyme. Other biochemical properties are also reported.