Stuart factor

X Stuart factor Both Activated form (Xa) converts prothrombin to thrombin... 

Pharmacology Vitamin K promotes the hepatic synthesis of active prothrombin (factor II), proconvertin (factor VII), plasma thromboplastin component (factor IX), and Stuart factor (factor X). The mechanism by which vitamin K promotes formation of these clotting factors involves the hepatic post-translational carboxylation of specific glutamate residues to gamma-carboxylglutamate residues in proteins involved in coagulation, thus leading to their activation. 

Vitamin K activity is associated with several quinones, including phylloquinone (vitamin Kj), menadione (vitamin K3), and a variety of menaquinones (vitamin K2). These quinones promote the synthesis of proteins that are involved in the coagulation of blood. These proteins include prothrombin, factor VII (proconvertin), factor IX (plasma thromboplastin), and factor X (Stuart factor). A detailed discussion of blood coagulation is found in Chapter 22. The vitamin K quinones are obtained from three major sources. Vitamin K is present in vari-... 

DiScipio RG, Hermodson MA, Davie EW. Activation of human factor X (Stuart factor) by a protease from Russell s viper venom. Biochemistry 1977 16 5253- 5260. 

X Stuart factor 50kD a glycoprotein composed of a light and a heavy chain. 

Tissue thromboplastin (III), Stuart factor (X), proconvertin (VII), and calcium (IV)... 

A protein called Stuart factor cleaves prothrombin, turning it into active thrombin that can then cleave fibrinogen to fibrin to form the blood clot.3 Unfortunately, as you may have guessed, if Stuart factor, prothrombin, and fibrinogen were the only blood-clotting proteins, then Stuart factor would rapidly trigger the cascade, congealing all... 

At this point there s a little twist to our developing chicken-and-egg scenario. Even activated Stuart factor can t turn on prothrombin. Stuart factor and prothrombin can be mixed in a test tube for longer than it would take a large animal to bleed to death without any noticeable production of thrombin. It turns out that another protein, called accelerin, is needed to increase the activity of Stuart factor. The dynamic duo—accelerin and activated Stuart factor— cleave prothrombin fast enough to do the bleeding animal some good. So in this step we need two separate proteins to activate one proenzyme. 

But it still seems we haven t made much progress—now we have to go back and ask what activates Stuart factor. It turns out that it can be activated by two different routes, called the intrinsic and the extrinsic pathways. In the intrinsic pathway, all the proteins required for clotting are contained in the blood plasma in the extrinsic pathway, some clotting proteins occur on cells. Let s first examine the intrinsic pathway. (Please follow along using Figure 4-3.)... 

The intrinsic and extrinsic pathways cross over at several points. Hageman factor, activated by the intrinsic pathway, can switch on proconvertin of the extrinsic pathway. Convertin can then feed back into the intrinsic pathway to help activated PTA activate Christmas factor. Thrombin itself can trigger both branches of the clotting cascade by activating antihemophilic factor, which is required to help activated Christmas factor in the conversion of Stuart factor to its active form, and also by activating proconvertin. ... 

One could imagine a blood-clotting system that was somewhat simpler than the real one—where, say, Stuart factor, after activation by... 

Yang Stuart factor appears, a duplicate] of the recently gla-anointed prothrombin its ability to bind to proaccelerin can bring about... activation... 

Yang again Proconvertin is duplicated from Stuart factor, liberating prothrombin for better binding to fibrin. When combined with tissue factor, proconvertin is able to activate Stuart factor by [cutting it). 

Yang again Christmas factor from Stuart factor. For a period, both bind to proaccelerin. 

Figure 5.3. Intrinsic and extrinsic blood clotting cascades. Factor I, fibrinogen Factor II, prothrombin (vitamin K-dependent) Factor HI, thromboplastin Factor V, proac-celerin Factor VII, proconvertin (vitamin K-dependent) Factor VIII, antihemophilic factor Factor IX, Christmas factor (vitamin K-dependent) Factor X, Stuart factor (vitamin K-dependent) Factor XI, plasma thromboplastin Factor XII, Hageman factor Factor XIII, fibrin-stabilizing factor and Factor XIV protein C (vitamin K-dependent). What was at one time called Factor IV is calcium no factor has been assigned number...

X Stuon Power factor. Stuart factor, autopmthrombin til... 

S.G., Davie, E.W. 1977. A comparison of human prothrombin, factor IX (Ghristmas factor), factor X (Stuart factor), and protein S, Biochemistry 16, 698-706. 

Hageman factor (XII), antihemophihc globuhn (VIII), Christmas factor (IX), plasma diromboplastin antecedent (XI), calcium (IV), and platelet phospholipids Tissue diromboplastin (III), Stuart factor (X), proconvertin (VII), and calcium (IV)... 

Antihemophilic factor, Factor VIII, a protein (Mr 265 kDa) acting as component of the blood clotting cascade in humans. Activated Factor VIIT acts as an accessory factor during the activation of Factor X Stuart factor) by activated Christmas factor IXa. Factor VIII forms a complex with the Willebrandt factor during circulation in blood [T. Halkier, Mechanisms in Blood Coagulation, Fibrinolysis and the Complement System, Cambridge University Press, 1991]. 

Stuart-Factor, Stuart Prower-Factor, Thrombokinase, Factor X... 

Stuart-Factor, Stuart Prower-Factor, Thrombokinase, Factor X, a serine protease and constituent of the blood coagulation cascade. It is either be activated by factor IX (intrinsic pathway) or by Factor Vila (extrinsic pathway). In complex with Factor V as the cofactor it cleaves prothrombin at Arg-Thr and Arg-Ile to give active thrombin. 

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