Factor XII Proteins and Enzymes

Coagulation factor XII, also called Hageman factor, circulates in blood as a zymogen. This single chain zymogen is activated by contact with negatively charged polyanions,to form a two chain serine protease containing alpha factor XIIa. The heavy chain contains two fibronectin type domains, two epidermal growth factor (EGF) like domains, a kringle domain and a proline rich domain, whereas the light chain contains only a catalytic domain. On activation, further cleavages takes place in the heavy ...