General descriptionThrombin is the final coagulation protease in regard to hemostasis, promoting both procoagulant and anticoagulant effects. Thrombin comprises of A-chain and B-chain with the catalytic pocket. The C-terminal regions has a fibrinogen recognition site (FRS) and a heparin binding site (HBS). The main function of thrombin is cleavage of fibrinogen to fibrin. It coordinates the coagulation cascade and coordinates with protease-activated receptors (PARs) to regulate physiological functions. High levels of thrombin causes neurotoxicity in dopaminergic neurons and contribute to the progression of parkinsons disease. Altered thrombin levels modulates coagulation pathway in multiple sclerosis. Patients with coronary artery disease (CAD) show elevated levels of thrombin.
ApplicationThrombin is used for site specific cleavage of recombinant fusion proteins containing an accessible thrombin recognition site for removal of affinity tags. Thrombin has been used in a study to evaluate coagulation abnormalities in acute liver failure.
Thrombin from bovine plasma may be used:
- for the generation of fibrin from fibrinogen embedded in microbubbles
- for the cleavage of hydrogenase maturation protein (HypF-N) from the nickel resin
as revitalization model to mimic blood fabrication in root canal
Biochem/physiol Actions
Serine protease that selectively cleaves Arg-Gly bonds in fibrinogen to form fibrin and fibrinopeptides A and B.
Physical form
Lyophilized powder containing sodium chloride and Tris-HCl, pH 7.0
Preparation Note
Traditional thrombin products are activated with bovine brain thromboplastin, whereas T7326 is activated with bovine lung thromboplastin and does not contain any bovine brain products in its preparation.
Analysis Note
Activity is expressed in NIH units obtained by direct comparison to a NIH Thrombin Reference Standard, Lot K.
The NIH assay procedure uses 0.2 mL of diluted plasma (1:1 with saline) as a substrate and 0.1 mL 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.
Other Notes
Activity is expressed in NIH units obtained by direct comparison to a NIH thrombin reference standard.
View more information on thrombin at www.sigma-aldrich.com/enzymeexplorer. 
