High molecular weight kininogen (HMWK)

a plasma protein of 110,000 molecular weight that normally exists in plasma in a 1:1 complex with prekallikrein. The complex is a cofactor in the activation of coagulation factor XII. The product of this reaction, XIIa, in turn activates prekallikrein to kallikrein. SYN: Fitzgerald factor, Flaujeac factor, Williams factor.