Fibrinolytic proteases have potential applications in cardiovascular disease therapy. A novel fibrinolytic protease， AfeE， with strong thrombolytic activity was purified from Streptomyces sp. CC5. AfeE displayed maximum activity at 40°C in the pH range of 7.0-12.0. It was strongly inhibited by serine protease inhibitor phenylmethanesulfonylfluoride， soybean trypsin inhibitor， tosyl-l-lysine chloromethyl ketone and tosyl-l-phenylalanine chloromethyl ketone. The activity of the enzyme was partially inhibited by Cu(2+)， Co(2+) and Zn(2+). AfeE exhibited higher substrate specificity for fibrin than fibrinogen， which has rarely been reported in fibrinolytic enzymes. AfeE also showed high thrombolytic ac... More
Fibrinolytic proteases have potential applications in cardiovascular disease therapy. A novel fibrinolytic protease， AfeE， with strong thrombolytic activity was purified from Streptomyces sp. CC5. AfeE displayed maximum activity at 40°C in the pH range of 7.0-12.0. It was strongly inhibited by serine protease inhibitor phenylmethanesulfonylfluoride， soybean trypsin inhibitor， tosyl-l-lysine chloromethyl ketone and tosyl-l-phenylalanine chloromethyl ketone. The activity of the enzyme was partially inhibited by Cu(2+)， Co(2+) and Zn(2+). AfeE exhibited higher substrate specificity for fibrin than fibrinogen， which has rarely been reported in fibrinolytic enzymes. AfeE also showed high thrombolytic activity in a carrageenan-induced mouse tail thrombosis model. AfeE prolonged prothrombin time， activated partial thromboplastin time， and thrombin time in rat blood. A bleeding time assay revealed that AfeE did not prolong bleeding time in mice at a dose of 1mg/kg. No acute cytotoxicity was observed for AfeE at 320μg/well in human umbilical vein endothelial cells. The afeE gene was cloned from the genome of Streptomyces sp. CC5. Full-length AFE-CC5E contained 434 amino acids and was processed into a mature form consisting 284 amino acids by posttranslational modification， as revealed by high-resolution mass spectrometry analysis. These results indicate that AfeE is a prospective candidate for antithrombotic drug development.
