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Prothrombin fragment 1+2 (F1+2), also written as prothrombin fragment 1.2 (F1.2), is a polypeptide fragment of prothrombin (factor II) generated by the in vivo cleavage of prothrombin into thrombin (factor IIa) by the enzyme prothrombinase (a complex of factor Xa and factor Va). [1] [2] [3] It is released from the N-terminus of prothrombin. [3]
Clotting time is a general term for the time required for a sample of blood to form a clot, or, in medical terms, coagulate.The term "clotting time" is often used when referring to tests such as the prothrombin time (PT), activated partial thromboplastin time (aPTT or PTT), activated clotting time (ACT), thrombin time (TT), or Reptilase time.
Coagulation activation markers are biomarkers of net activation of coagulation and fibrinolysis. [1] [2] Examples include prothrombin fragment 1+2 (F1+2), thrombin–antithrombin complex (TAT), fibrinopeptide A (FpA), fibrin monomers (FMs), plasmin-α 2-antiplasmin complex (PAP), activated protein C–protein C inhibitor (APC-PCI), and D-dimer (DD).
Further, the final common pathway scheme implies that prothrombin is converted to thrombin only when acted upon by the intrinsic or extrinsic pathways, which is an oversimplification. In fact, thrombin is generated by activated platelets at the initiation of the platelet plug, which in turn promotes more platelet activation. [32]
The prothrombin time ratio is the ratio of a subject's measured prothrombin time (in seconds) to the normal laboratory reference PT. The PT ratio varies depending on the specific reagents used, and has been replaced by the INR. [3] Elevated INR may be useful as a rapid and inexpensive diagnostic of infection in people with COVID-19. [4]
To produce thrombin, the prothrombinase complex cleaves two peptide bonds in prothrombin, one after Arg 271 and the other after Arg 320. [1] Although it has been shown that factor Xa can activate prothrombin when unassociated with the prothrombinase complex, the rate of thrombin formation is severely decreased under such circumstances.
Thrombin (Factor IIa) (EC 3.4.21.5, fibrose, thrombase, thrombofort, topical, thrombin-C, tropostasin, activated blood-coagulation factor II, E thrombin, beta-thrombin, gamma-thrombin) is a serine protease, that converts fibrinogen into strands of insoluble fibrin, as well as catalyzing many other coagulation-related reactions.
Coagulation tests such as prothrombin time (PT) and partial thromboplastin time (PTT) and thrombin time (TT). Tube must be filled to the proper line. Plain red No additive: Serum: Total complement activity, cryoglobulins: Gold (sometimes red and grey "tiger top" [3]) Clot activator and serum separating gel [4]