Biomaterial Database

The role of factor VIII in the activation of human blood coagulation factor X by activated factor IX. 1985

K Mertens, and A van Wijngaarden, and R M Bertina

The role of factor VIII in the activation of human factor X by factor IXa, Ca2+ and phospholipid has been investigated. Factor VIII stimulated the factor Xa formation after activation by factor Xa or thrombin; the activity of thrombin-activated factor VIII was about 4-fold that of factor Xa-activated factor VIII. The isolated procoagulant moiety of the factor VIII complex behaved identically to the complete complex, whereas the von Willebrand factor moiety did not participate in the factor Xa formation. Thrombin-activated factor VIII complex (factor VIIIa) was used to study the effect of factor VIIIa in kinetic experiments. The results revealed a complex kinetic behaviour, including substrate inhibition and non-linearity of the reaction rate with the enzyme concentration. Using previously obtained insight into the kinetics of factor X activation in the absence of factor VIII, the results were found to support the hypothesis that factor VIIIa participates in the factor Xa formation in a complex with phospholipid-bound factor IXa; the formation of the factor VIIIa-factor IXa complex then increases the catalytic efficiency of the factor IXa by 500-fold.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010743	Phospholipids	Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.	Phosphatides,Phospholipid
D001777	Blood Coagulation	The process of the interaction of BLOOD COAGULATION FACTORS that results in an insoluble FIBRIN clot.	Blood Clotting,Coagulation, Blood,Blood Clottings,Clotting, Blood
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D005164	Factor IX	Storage-stable blood coagulation factor acting in the intrinsic pathway of blood coagulation. Its activated form, IXa, forms a complex with factor VIII and calcium on platelet factor 3 to activate factor X to Xa. Deficiency of factor IX results in HEMOPHILIA B (Christmas Disease).	Autoprothrombin II,Christmas Factor,Coagulation Factor IX,Plasma Thromboplastin Component,Blood Coagulation Factor IX,Factor 9,Factor IX Complex,Factor IX Fraction,Factor Nine,Factor IX, Coagulation
D005169	Factor VIII	Factor VIII of blood coagulation. Antihemophilic factor that is part of the factor VIII/von Willebrand factor complex. Factor VIII is produced in the liver and acts in the intrinsic pathway of blood coagulation. It serves as a cofactor in factor X activation and this action is markedly enhanced by small amounts of thrombin.	Coagulation Factor VIII,Factor VIII Clotting Antigen,Factor VIII Coagulant Antigen,Factor VIII Procoagulant Activity,Thromboplastinogen,Blood Coagulation Factor VIII,F VIII-C,Factor 8,Factor 8 C,Factor Eight,Factor VIIIC,Hyate-C,Hyatt-C,F VIII C,Hyate C,HyateC,Hyatt C,HyattC
D005170	Factor X	Storage-stable glycoprotein blood coagulation factor that can be activated to factor Xa by both the intrinsic and extrinsic pathways. A deficiency of factor X, sometimes called Stuart-Prower factor deficiency, may lead to a systemic coagulation disorder.	Autoprothrombin III,Coagulation Factor X,Stuart Factor,Stuart-Prower Factor,Blood Coagulation Factor X,Factor 10,Factor Ten,Stuart Prower Factor,Factor X, Coagulation
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D015944	Factor VIIIa	Activated form of factor VIII. The B-domain of factor VIII is proteolytically cleaved by thrombin to form factor VIIIa. Factor VIIIa exists as a non-covalent dimer in a metal-linked (probably calcium) complex and functions as a cofactor in the enzymatic activation of factor X by factor IXa. Factor VIIIa is similar in structure and generation to factor Va.	Coagulation Factor VIIIa,Factor VIII, Activated,Factor VIII, Thrombin-Activated,Blood Coagulation Factor VIII, Activated,Factor 8A,Factor Eight A,Factor VIIIa Heavy Chain, 200 kDa Isoform,Factor VIIIa Heavy Chain, 92 kDa Isoform,Factor VIIIa Light Chain,Activated Factor VIII,Factor VIII, Thrombin Activated,Factor VIIIa, Coagulation,Thrombin-Activated Factor VIII
D015949	Factor IXa	Activated form of factor IX. This activation can take place via the intrinsic pathway of blood coagulation by the action of factor XIa and calcium, or via the extrinsic pathway by the action of factor VIIa, thromboplastin, and calcium. Factor IXa serves to activate factor X to Xa by cleaving the arginyl-leucine peptide bond in factor X.	Coagulation Factor IXa,Factor IX, Activated,Blood Coagulation Factor IX, Activated,Factor 9A,Factor Nine A,Activated Factor IX,Factor IXa, Coagulation