title: Purification and properties of a fibrinogenase from the venom of Naja nigricollis.
abstract: A fibrinogenolytic proteinase from the venom of Naja nigricollis was purified by chromatography on Bio-Rex 70 and Phenyl-Sepharose. The purified enzyme, designated proteinase F1, was homogeneous by the criterion of SDS-polyacrylamide gel electrophoresis, and consisted of a single chain with a molecular weight of 58,000. Purified proteinase F1 had approximately 15-fold more proteinase activity than the crude venom, based on its ability to inactivate alpha 2-macroglobulin. The enzyme acted on only the A alpha-chain of fibrinogen and left the B beta- and gamma-chains intact. The pH optimum for this fibrinogenolytic activity was in the range of pH 8 to 10. In addition to its activity on fibrinogen, proteinase F1 was active on alpha 2-macroglobulin and fibrinonectin, but did not degrade casein, hemoglobin or bovine serum albumin. The enzyme was not inhibited by inhibitors of serine proteinases, cysteine proteinases or acid proteinases, but only by the metalloproteinase inhibitor, EDTA. The inhibition by EDTA could be prevented by Zn2+, but not by Ca2+ or Mg2+.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D004546:Elapid Venoms / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000378:metabolism; D013379:Substrate Specificity; D013917:Thrombin / Q000302:isolation & purification*
chemical_list: D000596:Amino Acids; D004546:Elapid Venoms; D005340:Fibrinogen; D004492:Edetic Acid; D013917:Thrombin; D008274:Magnesium; D002118:Calcium