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The catalytic domain is released from prothrombin fragment 1.2 to create the active enzyme thrombin, which has a molecular weight of 36,000 Da. Structurally, it is a member of the large PA clan of proteases. Prothrombin is composed of four domains; an N-terminal Gla domain, two kringle domains and a C-terminal trypsin-like serine protease domain.
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 The PT ratio varies depending on the specific reagents used, and has been replaced by the INR.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]
Liver function tests (LFTs or LFs), also referred to as a hepatic panel or liver panel, are groups of blood tests that provide information about the state of a patient's liver. [1] These tests include prothrombin time (PT/INR), activated partial thromboplastin time (aPTT), albumin , bilirubin (direct and indirect), and others.
The prothrombinase complex catalyzes the conversion of prothrombin (factor II), an inactive zymogen, to thrombin (factor IIa), an active serine protease. The activation of thrombin is a critical reaction in the coagulation cascade, which functions to regulate hemostasis in the body.
It acts by cleaving prothrombin in two places (an Arg-Thr and then an Arg-Ile bond), which yields the active thrombin. This process is optimized when factor Xa is complexed with activated co-factor V in the prothrombinase complex. Factor Xa is inactivated by protein Z-dependent protease inhibitor (ZPI), a serine protease inhibitor (serpin).
Prothrombin activator is a complex of a dozen blood coagulation factors that functions in catalyzing prothrombin into thrombin. Prothrombin activator is released in the body by a cascade of chemical reactions in response to damage in a blood vessel.
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.
Coagulase reacts with prothrombin in the blood. The resulting complex is called staphylothrombin, which enables the enzyme to act as a protease to convert fibrinogen, a plasma protein produced by the liver, to fibrin. This results in clotting of the blood.