Coagulogen is a gel-forming protein of hemolymph; it hinders the spread of invaders by immobilizing them. Coagulogen is cleaved after Arg-38 and Arg-66 by a clotting enzyme contained in the hemocyte and activated by a bacterial endotoxin (lipopolysaccharide). This cleavage releases the peptide C and leaves 2 chains of coagulin, A and B, linked by two disulfide bonds. Coagulin molecules interlink to form a gel. Hemolymph. The sequence shown is that of coagulogen-1. Belongs to the coagulin family.