Merck, H7016-2KU, Hirudin from leeches

General description
Hirudin is a 7 kDa acidic protein containing 65 amino acid residues that has an isoelectric point of 3.5-4.0. It is not glycosylated and lacks tryptophan, arginine and methionine residues. It is chemically stable between pH 2-12 and at temperatures up to 80°C.
Biochem/physiol Actions
The anticoagulant, hirudin, is the most potent natural inhibitor of both soluble and clot-bound thrombin. It binds thrombin with high affinity, covering more than 20% of its surface area and occluding both the active site and exosite I (fibrinogen and PAR recognition site). Hirudin blocks thrombus growth and platelet activation. It is not metabolized in the bloodstream of humans and is eliminated unchanged via kidney filtration.
The anticoagulant, hirudin, is the most potent natural inhibitor of both soluble and clot-bound thrombin. It forms a high-affinity 1:1 complex with thrombin, occluding both the proteolytic site and exosite I (fibrinogen and PAR recognition site). Hirudin blocks thrombus growth and platelet activation, and has been suggested as the clinically preferred anticoagulant (over heparin and citrate) for its specific mode of action and absence of side effects. It is not metabolized in the bloodstream of humans and is eliminated unchanged via kidney filtration.
Analysis Note
Protein determined by Lowry.
Other Notes
One unit (ATU) will neutralize one NIH unit of thrombin at 37 °C, based on direct comparison to an NIH thrombin reference standard.