Subtilisin-like serine protease. Cleaves prothrombin at 151-Ala-|-Met-152, 271-Arg-|-Thr-272 and 316-Tyr-|-Ile-317 to produces meizothrombin(desF1)-like molecules. Degrades fibinogen. Inhibits plasma coagulation. Strongly inhibited by antipain, PMSF and aprotinin. Inhibited by benzamidine by 49%. Little or no inhibition by EDTA, E-64, iodoacetic acid, leupeptin and FUT-175. Optimum pH is 8.0. Optimum temperature is 55 degrees Celsius. Homodimer or multimer. Belongs to the peptidase S8 family.