Characterization of a fibrinogenase from northern copperhead (Agkistrodon contortrix mokasen) venom.

One of the fractions obtained by the carboxymethylcellulose ion-exchange chromatography of northern copperhead (Agkistrodon contortrix mokasen) venom prevented the thrombin-induced clotting of fibrinogen by proteolytically degrading the fibrinogen. The active component has been further purified to apparent electrophoretic homogeneity by molecular sieve chromatography. Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis indicated a molecular weight of 22 900 +/- 600 for the purified enzyme. In addition to its fibrinogenase activity, it catalyzed the hydrolysis of hide power azure and had an intraperitoneal LD50 value in mice of less than 5.1 microgram/g body weight. The enzyme rapidly destroyed fibrinogen's ability to form clots. Electrophoresis of fibrinogen which had been incubated only a few minutes with the fibrinogenase revealed the rapid disappearance of the alpha-chain and the appearance of lower molecular weight fragments. The neutral pH optimum and ethylenediamine-tetraacetic acid (EDTA) and dithiothreitol sensitivity indicated that this enzyme belonged to the class metalloproteinases. Atomic absorption studies have revealed one zinc atom per molecule of protein. The apoenzyme's activity was restored by incubation with ZnCl2.