Snake venom serine protease that cleaves fibrinogen Aalpha chain (FGA), partially cleaves Bbeta chain (FGB) and has no activity on gamma chain. Is more potent than A3 alpha-fibrinogenases and less potent than A1. 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.