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Prothrombin
Synonym(s)
DefinitionThis section has been translated automatically.
Prothrombin (factor II) is an enzyme synthesized in the liver and is vitamin K-dependent.
The biosynthesis of prothrombin takes place from a single peptide chain. The prothrombin has a molecular weight of 69,000 D. In electrophoresis it is detectable in the alpha-2 or beta fraction. It carries 10 Ca++ binding sites per molecule to which the prothrombinase binds. The plasma concentration is 10-15 mg/dI. Prothrombin is also detectable in the lymph and extravasally.
The half-life of factor II is 41-72 hours. Prothrombin is activated by the prothrombinase complex(F-Xa, phospholipids, Ca++, factor Va) to form thrombin (factor IIa).
The prothrombin fragments are a measure of thrombin formation and thus also of the activity of the coagulation system.
The prothrombin concentration is given in percent (normally approx. 100%). Prothrombin is increased after administration of vitamin K, under ovulation inhibitors, in the context of hyperlipidemia and in the early phase of consumption coagulopathy.
LiteratureThis section has been translated automatically.
- HA Neumann (2014) The coagulation system. ABW-Wissenschaftsverlag GmbH Berlin S. 50f.