Snake venom serine protease that selectively cleaves the heavy chain of protein C (PROC). This activation is thrombomodulin-independent. Monomer. Expressed by the venom gland. Is used in diagnostic practice for the determination of disorders in the PC pathway. Functional assays are either clotting assays or based on determinations using chromogenic assays. Sold under the name Protac by Pentapharm. Belongs to the peptidase S1 family. Snake venom subfamily.