Clostripain (EC188.8.131.52, clostridiopeptidase B, clostridium histolyticum proteinase B, alpha-clostridipain, clostridiopeptidase, Endoproteinase Arg-C) is a proteinase that cleaves proteins on the carboxyl peptide bond of arginine. It was isolated from Clostridium histolyticum. The isoelectric point of the enzyme is 4.8-4.9 (at 8°C), and optimum pH is 7.4~7.8 (against α-benzoyl-arginine ethyl ester). The composition of the enzyme is indicated to be of two chains of relative molecular mass 45,000 and 12,500.
^Gilles, A.-M.; Imhoff, J.-M.; Keil, B. (1979). "α-Clostripain. Chemical characterization, activity, and thiol content of the highly active form of clostripain". J. Biol. Chem. 254: 1462–1468. PMID762145.