Thrombin-like snake venom serine protease. Releases both fibrinopeptides A and B from fibrinogen (FGA and FGB) to form fibrin clots. Also activates factor XIII (F13A). The activity of the enzyme is stabilized by calcium ion. Preferential cleavage: Arg-|-Xaa bonds in fibrinogen to form fibrin and release fibrinopeptides A and B. Inhibited by PMSF, but not by heparin, hirudin and antithrombin-III. Optimum temperature is 30 degrees Celsius with tosyl-Arg-methyl ester (TAME) as substrate and 37 degrees Celsius with natural substrates. Monomer. Expressed by the venom gland. Glycosylated. Contains five disulfide bonds. Belongs to the peptidase S1 family. Snake venom subfamily.