title: Enzymological characterization of FII(a), a fibrinolytic enzyme from Agkistrodon acutus venom.
abstract: OBJECTIVE
  To study the enzymological characterization of a fibrinolytic enzyme (FII(a)) 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 FII(a) was determined by atomic absorption spectroscopy.
  
  
  RESULTS
  After incubation with FII(a) (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 (3171+/-25 mg/kg), potassium (489+/-17 mg/kg) and calcium (319+/-13 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.
  
  
  CONCLUSIONS
  FIIa can degrade the Aalpha-, Bbeta- and gamma-chains of fibrinogen. FII(a) is a metalloproteinase, and Zn2+, Ca2+, and disulfide bonds are necessary for its fibrinogenolytic activity.
authors.affiliation: Department of Pharmacology, Zhongshan Medical College, Sun Yat-Sen University, Guangzhou 510080, China.
authors.forename: Xiu-Xia
authors.initials: XX
authors.lastname: Liang
authors.forename: Ying-Na
authors.initials: YN
authors.lastname: Zhou
authors.forename: Jia-Shu
authors.initials: JS
authors.lastname: Chen
authors.forename: Peng-Xin
authors.initials: PX
authors.lastname: Qiu
authors.forename: Hui-Zhen
authors.initials: HZ
authors.lastname: Chen
authors.forename: Huan-Huan
authors.initials: HH
authors.lastname: Sun
authors.forename: Yu-Ping
authors.initials: YP
authors.lastname: Wu
authors.forename: Guang-Mei
authors.initials: GM
authors.lastname: Yan
mesh_terms: D017836:Agkistrodon; D000818:Animals; D002118:Calcium / Q000032:analysis; D002122:Calcium Chloride / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D003435:Crotalid Venoms / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D003545:Cysteine / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D005340:Fibrinogen / Q000378:metabolism*; D005342:Fibrinolysis / Q000187:drug effects*; D005343:Fibrinolytic Agents / Q000302:isolation & purification / Q000378:metabolism*; D015636:Magnesium Chloride / Q000494:pharmacology; D008666:Metalloendopeptidases; D045726:Metalloproteases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism; D011188:Potassium / Q000032:analysis; D015032:Zinc / Q000032:analysis; D017967:Zinc Compounds / Q000494:pharmacology
chemical_list: D002712:Chlorides; D003435:Crotalid Venoms; D005343:Fibrinolytic Agents; D017967:Zinc Compounds; D015636:Magnesium Chloride; D004533:Egtazic Acid; C016837:zinc chloride; D005340:Fibrinogen; D004492:Edetic Acid; D045726:Metalloproteases; C478420:FIIa; D008666:Metalloendopeptidases; D015032:Zinc; D003545:Cysteine; D002122:Calcium Chloride; D011188:Potassium; D002118:Calcium; D004229:Dithiothreitol