Enzymological characterization of FIIa, a fibrinolytic enzyme from Agkistrodon acutus venom
Abstract
Aim: To study the enzymological characterization of a fibrinolytic enzyme (FIIa) from Agkistrodon acutus venom.
Methods: The fibrinogenolytic effect and the influences of several protease inhibitors, chelating agents, and metal ions on fibrinogenolytic activity were visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The metal content of FIIa was determined by atomic absorption spectroscopy.
Results: After incubation with FIIa (0.25 g/L), Aalpha-, Bbeta- and gamma-chains of fibrinogen disappeared within 5 min, 30 min, and 8 h, respectively. The molecular weights of major degradation products were 45 000 and 41 000, which were different from those bands produced by plasmin. The fibrinogenolytic activity of FIIa was strongly inhibited by ethylenediamine tetraacetic acid (EDTA), ethyleneglycol tetraacetic acid (EGTA), dithiothreitol and cysteine, but not by phenylmethyl-sulfonyl fluoride and soybean trypsin inhibitor. Zinc (3171plusminus25 mg/kg), potassium (489plusminus17 mg/kg) and calcium (319plusminus13 mg/kg) were found in FIIa. Zn2+, Ca2+ and Mg2+ could recover the fibrinogenolytic activity of FIIa, which was inhibited by EDTA. Only Ca2+ could recover the fibrinogenolytic activity inhibited by EGTA.
Conclusion: FIIa can degrade the Aalpha-, Bbeta- and gamma-chains of fibrinogen. FIIa is a metalloproteinase, and Zn2+, Ca2+, and disulfide bonds are necessary for its fibrinogenolytic activity.
Keywords:
Methods: The fibrinogenolytic effect and the influences of several protease inhibitors, chelating agents, and metal ions on fibrinogenolytic activity were visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The metal content of FIIa was determined by atomic absorption spectroscopy.
Results: After incubation with FIIa (0.25 g/L), Aalpha-, Bbeta- and gamma-chains of fibrinogen disappeared within 5 min, 30 min, and 8 h, respectively. The molecular weights of major degradation products were 45 000 and 41 000, which were different from those bands produced by plasmin. The fibrinogenolytic activity of FIIa was strongly inhibited by ethylenediamine tetraacetic acid (EDTA), ethyleneglycol tetraacetic acid (EGTA), dithiothreitol and cysteine, but not by phenylmethyl-sulfonyl fluoride and soybean trypsin inhibitor. Zinc (3171plusminus25 mg/kg), potassium (489plusminus17 mg/kg) and calcium (319plusminus13 mg/kg) were found in FIIa. Zn2+, Ca2+ and Mg2+ could recover the fibrinogenolytic activity of FIIa, which was inhibited by EDTA. Only Ca2+ could recover the fibrinogenolytic activity inhibited by EGTA.
Conclusion: FIIa can degrade the Aalpha-, Bbeta- and gamma-chains of fibrinogen. FIIa is a metalloproteinase, and Zn2+, Ca2+, and disulfide bonds are necessary for its fibrinogenolytic activity.