Limulus clotting factor C

Limulus clotting factor overbar C (, factor C, limulus factor C) is an enzyme. 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

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.