Snake venom serine protease that completely cleaves fibrinogen Aalpha chain (FGA), partially cleaves Bbeta chain (FGB) and has no activity on gamma chain. Is more potent that A2 and A3 alpha-fibrinogenases. Very active within 5 minutes. Inhibited by PMSF, bovine aprotinin (APR), and soybean trypsin inhibitor (STI). Is not inhibited by EDTA, beta-mercaptoethanol, and high temperature (85 degrees Celsius). Monomer. Expressed by the venom gland. Belongs to the peptidase S1 family. Snake venom subfamily.