Contact-activated fibrinolysis: role of surface concentration and high-molecular-weight kininogen.
Activation of plasminogen through contact-activated reactions involves participation of HF, PK, PTA, and HMWK. The concentration of negatively charged surface (kaolin) to which purified factors are exposed critically influences the extent to which the known enzymatic species participate in plasminogen activation as assayed upon a synthetic amide substrate and by fibrinolysis. HMWK is an essential cofactor for activation of plasminogen by PTA and for optimal plasminogen activation by kallikrein in the presence of kaolin. At a given kaolin concentration, HMWK reduces HF binding to kaolin and diminishes plasminogen activation by HF. In the presence of kaolin, HMWK also enhances the activity of plasmin against both synthetic substrates and fibrin.
D005174:Factor XII / Q000378:metabolism; D005342:Fibrinolysis; D006801:Humans; D007616:Kaolin / Q000378:metabolism; D007704:Kininogens / Q000502:physiology*; D010958:Plasminogen / Q000378:metabolism; D011288:Prekallikrein / Q000378:metabolism; D013925:Thromboplastin / Q000378:metabolism
D007704:Kininogens; D007616:Kaolin; D005174:Factor XII; D010958:Plasminogen; D013925:Thromboplastin; D011288:Prekallikrein