Aprotinin is a multiple inhibitor of many serine proteases, including Trypsin, Plasmin, Urokinase, Kallikrein, and Factor XIIa. It contains 58 amino acids. It forms stable complexes with these enzymes. Aprotinin can be used in any application where inhibitor of its targeted proteases is needed. Current uses concern protein isolation, removal of reactive proteases through solid phase, inhibition of undesired proteolytic activity in laboratory assays, or other techniques; for blocking fibrinolytic activity in vitro. Can be restored with 5mL distilled water for obtaining a solution at about 50 mg/mL. Stable at 2-8°C up to the expiration date printed on the label; up to 6 months stored at below -20°C.