Thrombin

In order to stop local bleeding, thrombin, a natural thrombin drug that catalyzes the transformation of fibrinogen to fibrin, is frequently used. Thrombin is synthesized from cow plasma, and it is used to stop bleeding from open vessels when it is not possible to use other methods. It is used to stop light bleeding.

Thrombin is a trypsin-like serine protease involved in a multitude of processes in the human body. Thrombin generation is the result of limited proteolysis of the vitamin K-dependent zymogen prothrombin. Thrombin is the last enzyme in the clotting cascade functioning to cleave fibrinogen to fibrin which forms the fibrin gel of a haemostatic plug or a pathologic thrombus

Thrombin is a sterile protein substanceprepared from prothrombin of bovine origin. It is used as atopical hemostatic because it can clot blood, plasma, or a solutionof fibrinogen without addition of other substances.Thrombin also may initiate clotting when combined withgelatin sponge or fibrin foam.
For external use it is applied topically to the wound, as asolution containing 100 to 2,000 National Institutes ofHealth (NIH) units/mL in sodium chloride irrigation or sterilewater for injection or as a dry powder.

Thrombin is purified by chromatography on a DEAE-cellulose column, while eluting with 0.1M NaCl, pH 7.0, followed by chromatography on Sephadex G-200. The final preparation is free from plasminogen and plasmin. [Yin & Wessler J Biol Chem 243 112 1968.] Thrombin from bovine blood is also purified by chromatography using p-chlorobenzylamino--aminocaproyl agarose, and gel filtration through Sephadex G-25. [Thompson & Davie Biochim Biophys Acta 250 210 1971.] Thrombin from various species was purified initially by precipitation of impurities with rivanol. [Miller Nature 184 450 1959.] Tissue inhibitor of metalloproteins (TIMP, from human blood plasma), Mr ~30,000. These are purified by an [anti-human amniotic fluid-TIMP]-Sepharose immuno-affinity column and eluted with 50mM glycine/HCl pH 3.0 buffer that is 0.5M in NaCl, and followed by gel filtration [Cawston et al. Biochem J 238 677 1986].