Limulus clotting factor C

Limulus clotting factor overbar C (EC 3.4.21.84, factor C, limulus factor C) is an enzyme.^[1][2][3] This enzyme catalyses the following chemical reaction

Selective cleavage of -Arg¹⁰³-Ser- and -Ile¹²⁴-Ile- bonds in limulus clotting factor B to form factor overbar B.

Cleavage of -Pro-Arg- bonds in synthetic substrates

Limulus clotting factor overbar C
Identifiers
EC no.	3.4.21.84
CAS no.	115743-27-6
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
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Limulus clotting factor C
Identifiers
Organism	Tachypleus tridentatus
Symbol	?
UniProt	P28175
Search for Structures Swiss-model Domains InterPro

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.^[4] 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.^[5]