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Analysis Note

The NIH assay procedure uses 0.2 ml diluted plasma (1:1 with saline) as a substrate and 0.1ml of thrombin sample (stabilized in a 1% buffered albumin solution) based on a modification of the method of Biggs. Only clotting times in the range of 15-25 seconds are used for determining thrombin concentrations.

Application

Thrombin from human plasma has been:dissolved in CaC_l2 and added to poly ethylene glycolated fibrinogen/cell solution for fibrin productionto polymerize fibrin on well platesused as an endogenous agonist proteinase for proteinase-activated receptors : PAR1, PAR3 and PAR4 for stimulation of cells

Biochem/physiol Actions

Serine protease that selectively cleaves Arg-Gly bonds in fibrinogen to form fibrin and fibrinopeptides A and B.

Thrombin is an endolytic serine protease which stimulates vascular damage induced-leukocytes, platelets, endothelial and mesenchymal cell production. This action is mediated via G-protein-coupled receptor. It catalysis the cleavage of fibrinogen at Arg−Gly bonds to form fibrin and release fibrinopeptides A and B. The predominant form of thrombin in vivo is the zymogen prothrombin (factor II), which is produced in the liver. Prothrombin is a coagulation activation factor, high levels of which indicates cancer. Thrombin can be used to cleave fusion proteins. Cleavage of fusion proteins can be carried out at a thrombin:fusion protein ratio of 1:500.

General description

The F2 gene encodes thrombin protein and is mapped to human chromosome 11p11.2.

Other Notes

View more information on thrombin at www.sigma-aldrich.com/enzymeexplorer.

Physical form

Lyophilized from saline sodium citrate buffer, pH 6.5

Unit Definition

Activity is expressed in NIH units obtained by direct comparison to a NIH Thrombin Reference Standard