Ser- and -Ile124Ile- bonds in limulus clotting factor B to form factor 
. Cleavage of -Pro-Arg bonds in synthetic substrates
Reaction: Selective cleavage of -Arg103Ser- and -Ile124Ile- bonds in limulus clotting factor B to form factor . Cleavage of -Pro-Arg bonds in synthetic substrates
Other name(s): factor C; limulus factor C
Comments: From the hemocyte granules of the horseshoe crabs Limulus and Tachypleus. Factor C is activated by Gram-negative bacterial lipopolysaccharides and chymotrypsin. Inhibited by antithrombin III. In peptidase family S1 (trypsin family)
Links to other databases: BRENDA, EXPASY, KEGG, MEROPS, Metacyc, CAS registry number: 115743-27-6
References
1. Nakamura, T., Morita, T. and Iwanaga, S. Lipopolysaccharide-sensitive serine-protease zymogen (factor C) found in Limulus hemocytes. Isolation and characterization. Eur. J. Biochem. 154 (1986) 511-521. [PMID: 3512266]
2. Muta, T., Miyata, T., Misumi, Y., Tokunaga, F., Nakamura, T., Toh, Y., Ikehara, Y. and Iwanaga, S. Limulus factor C. An endotoxin-sensitive serine protease zymogen with a mosaic structure of complement-like, epidermal growth factor-like, and lectin-like domains. J. Biol. Chem. 266 (1991) 6554-6561. [PMID: 2007602]
3. Tokunaga, F., Nakajima, H. and Iwanaga, S. Further studies on lipopolysaccharide-sensitive serine protease zymogen (factor C): its isolation from Limulus polyphemus hemocytes and identification as an intracellular zymogen activated by α-chymotrypsin, not by trypsin. J. Biochem. (Tokyo) 109 (1991) 150-157. [PMID: 2016264]