Snake venom zinc metalloproteinase that calcium-independently catalyzes the conversion of prothrombin (F2) to alpha-thrombin through the formation of a thrombin intermediate. Binds 1 zinc ion per subunit. Inhibited by EDTA, but not by PMSF. Monomer. Expressed by the venom gland. Does not have an affect on factor X (F10) and fibrinogen. Belongs to the venom metalloproteinase (M12B) family. P-III subfamily. P-IIIa sub-subfamily.