High Molecular Weight Kininogen (HMWK)

High-molecular-weight kininogen (HMWK), is a protein from the blood coagulation system as well as the kinin-kallikrein system. It is a protein that adsorbs to the surface of biomaterials that come in contact with blood in vivo. This protein circulates throughout the blood and quickly adsorbs to the material surfaces.

HMWK is one of the early participants of the intrinsic pathway of coagulation, together with Factor XII (Hageman factor) and prekallikrein. It is 626 amino acids long, and weighs 88 to 120 kDa (dependent on glycosylation). The kininogen is not enzymatically active, and functions only as a cofactor for the activation of kallikrein and Hageman factor. It is also necessary for the activation of factor XI by factor XIIa. The histidine-rich region (amino acids 420 to 510) participates most strongly in coagulation.