Merck, 616370-100MGCN, Aprotinin, Bovine Lung, Crystalline

A competitive and reversible inhibitor of esterase and protease activity. Forms a tight complex with and blocks the active site of target enzymes. Inhibits a number of different proteases, including chymotrypsin, coagulation factors involved in the pre-phase of blood clotting, kallikrein (Kd = 1 X 10⁻⁷ M), plasmin (Kd = 2.3 X 10⁻¹⁰ M), tissue and leukocyte proteinases, and trypsin (Kd = 5 X 10⁻¹⁴ M). Does not inhibit Factor Xa or thrombin. Reported to be relatively acid and heat stable. Effectively inhibits target proteases at equimolar concentration. Useful as a serine proteinase inhibitor during purification of proteins and in studies of zymogen activation systems. Reported to suppress virus HA cleavage and limit reproduction of human and avian influenza viruses with a single arginine in the HA cleavage site.