Limulus clotting factor C - Misplaced Pages

Limulus clotting factor overbar C (EC 3.4.21.84, factor C, limulus factor C) is an enzyme. This enzyme catalyses the following chemical reaction

Selective cleavage of -Arg-Ser- and -Ile-Ile- bonds in limulus clotting factor B to form factor overbar B.

Cleavage of -Pro-Arg- bonds in synthetic substrates

This enzyme is isolated from the hemocyte granules of the horseshoe crabs Limulus and Tachypleus, where it serves as a LPS endotoxin-sensitive trypsin type serine protease to protect the organism from bacterial infection, initiating a cascade leading to coagulin formation. From the N-terminus to the C-terminus, the domains are:

EGF-like domain
3 Sushi domains
one LCCL domain and one C-type lectin domain
2 more Sushi domains
a trypsin domain

This enzyme is useful in Limulus amebocyte lysate as the endotoxin-detecting element. It can be produced recombinantly.

References

Nakamura T, Morita T, Iwanaga S (February 1986). "Lipopolysaccharide-sensitive serine-protease zymogen (factor C) found in Limulus hemocytes. Isolation and characterization". European Journal of Biochemistry. 154 (3): 511–21. doi:10.1111/j.1432-1033.1986.tb09427.x. PMID 3512266.
Muta T, Miyata T, Misumi Y, Tokunaga F, Nakamura T, Toh Y, et al. (April 1991). "Limulus factor C. An endotoxin-sensitive serine protease zymogen with a mosaic structure of complement-like, epidermal growth factor-like, and lectin-like domains". The Journal of Biological Chemistry. 266 (10): 6554–61. doi:10.1016/S0021-9258(18)38153-5. PMID 2007602.
Tokunaga F, Nakajima H, Iwanaga S (January 1991). "Further studies on lipopolysaccharide-sensitive serine protease zymogen (factor C): its isolation from Limulus polyphemus hemocytes and identification as an intracellular zymogen activated by alpha-chymotrypsin, not by trypsin". Journal of Biochemistry. 109 (1): 150–7. doi:10.1093/oxfordjournals.jbchem.a123337. PMID 2016264.
Iwanaga S (May 2007). "Biochemical principle of Limulus test for detecting bacterial endotoxins". Proceedings of the Japan Academy. Series B, Physical and Biological Sciences. 83 (4): 110–9. Bibcode:2007PJAB...83..110I. doi:10.2183/pjab.83.110. PMC 3756735. PMID 24019589.
Maloney T, Phelan R, Simmons N (October 2018). "Saving the horseshoe crab: A synthetic alternative to horseshoe crab blood for endotoxin detection". PLOS Biology. 16 (10): e2006607. doi:10.1371/journal.pbio.2006607. PMC 6200278. PMID 30312293.

External links

Limulus+clotting+factor+_overbar_C_ at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

v t e Endopeptidases: serine proteases/serine endopeptidases (EC 3.4.21)
Digestive enzymes	Enteropeptidase Trypsin Chymotrypsin Elastase Neutrophil Pancreatic
Coagulation	factors: Thrombin Factor VIIa Factor IXa Factor Xa Factor XIa Factor XIIa Kallikrein PSA KLK1 KLK2 KLK3 KLK4 KLK5 KLK6 KLK7 KLK8 KLK9 KLK10 KLK11 KLK12 KLK13 KLK14 KLK15 fibrinolysis: Plasmin Plasminogen activator Tissue plasminogen activator Urinary plasminogen activator
Complement system	Factor B Factor D Factor I MASP MASP1 MASP2 C3-convertase
Other immune system	Chymase Granzyme Tryptase Proteinase 3/Myeloblastin
Venombin	Ancrod Batroxobin
Other	Acrosin Prolyl endopeptidase Pronase Proprotein convertases 1 2 Prostasin Reelin Subtilisin/Furin/S1P4 Sedolisin/TPP1 Streptokinase Cathepsin A G

v t e Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)

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Biology

Category:

EC 3.4.21