Unreferenced date December 2009 In coagulation , the procoagulant protein factor X can be activated into factor Xa two ways. Extrinsic and intrinsic ways. The activating complexes are called tenase . Tenase is a contraction of ten and the suffix ase , which means, that the complex activate its substrate inactive factor X by cleaving it. Extrinsic tenase complex is made up of tissue factor , factor VII , and Ca2 Ca sup 2 sup as an activating ion. Intrinsic tenase complex contains the active factor IX IXa , its cofactor factor VIII VIIIa , the substrate factor X , and they are activated by negatively charged surfaces such as glass, active platelet membrane, sometimes cell membrane of monocytes . These vitamin K dependent procoagulant factors dock to this surface through their Gla domain with Ca sup 2 sup bridges. This makes the activating process much faster and blocks the binding of inhibitors. Category Coagulation system ... more details
being bound to vWF. FVIIIa is the co factor of FIXa, and together they form the tenase complex, which activates FX and so the cycle continues. Tenase is a contraction of ten and the suffix ase used for enzymes ... XIa activates FIX, which with its co factor FVIIIa form the tenase complex, which activates FX ... activation of FVIII and FIX to form the tenase complex, until it is down regulated by the anticoagulant ... are required for the tenase and prothrombinase complexes to function. Calcium mediates the binding ... with which it forms the tenase complex Haemophilia A Factor IX IX Antihemophilic factor B or Christmas factor Activates X forms tenase complex with factor VIII Haemophilia B Factor X X Stuart Prower ... more details
IX on the surface of activated platelets. The activated Factor IXa with Factor VIII a forms the tenasetenase complex . This tenase complex activates more Factor X, which in turn forms new prothrombinase ... more details
Scott syndrome is a rare congenital bleeding disorder that is due to a defect in a platelet mechanism required for blood coagulation . ref Weiss HJ. Scott syndrome a disorder of platelet coagulant activity PCA . Sem Hemat 1994 31 312 319 ref When normal platelets are activated, as may occur at sites of vascular injury, phosphatidylserine PS in the inner leaflet of the platelet membrane is transported to the outer membrane surface of the platelet, where it provides a binding site for plasma protein complexes, such as factor VIIIa IXa tenase and factor Va Xa prothrombinase , that are involved in the conversion of prothrombin to thrombin . ref Zwaal FA, Comfurius P, Bevers EM. Scott syndrome, a bleeding disorder caused by defective scrambling of membrane phospholipids. Biochem Bioph Acta 2004 1636 119 128 ref In Scott syndrome, the mechanism for translocating PS to the platelet membrane is defective, resulting in impaired thrombin formation. ref Rosing J, Bevers EM, Comfurius P, Hemker HC, von Dieijen G, Weiss HJ, et al. Impaired factor X and prothrombin activation associated with decreased phospholipid exposure in platelets from a patient with a bleeding disorder. Blood 1985 65 1557 1561. ref ref Toti F, Satta N, Fressinaud E, Meyer D, Freyssinet JM. Scott syndrome, characterized by impaired transmembrane migration of procoagulant phoshatidylserine and hemorrhagic complications, is an inherited disorder. Blood 1996 87 1409 1415 ref ref Elliott JI, Mumford AD, Albrecht C, Collins PW, Giddings JC, Higgins CF et al. Characterization of lymphocyte responses to Ca2 in Scott syndrome. Thromb Haemost 2004 91 412 415 ref A similar defect in PS translocation has also been demonstrated in Scott syndrome red blood cells and Epstein Barr virus transformed lymphocytes , suggesting that the defect in Scott syndrome reflects a mutation in a stem cell that effects multiple hematological lineages. The basis for the defect in PS translocation is, at present, unknown. A candidate protei ... more details
factor complex of the extrinsic coagulation pathway and by the tenase complex of the intrinsic pathway. The intrinsic tenase complex is composed of both Factor IX a and Factor VIII a. ref name pmid836809 ... more details
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