Aprotinin

Aprotinin is a polypeptide extracted from bovine lung and composed of 58 amino acids with a molecular weight of 6’512 Daltons. Aprotinin is a polyvalent reversible inhibitor of serine proteinases including plasmin and kallikrein. The active loop contains the reactive lysine residue in position 15, the tertiary structure shows a pear-shaped unit which fits exactly into the binding site of serine proteinases. Aprotinin slows down fibrinolysis, the process that leads to the breakdown of blood clots. In addition to its anti-fibrinolytic activity, aprotinin is also thought to preserve platelet function and have anti-inflammatory effects, both of which may be mediated by inhibition of protease-activated receptors expressed on platelets, vascular endothelium, and neutrophils.