Purity ~95% (RP-HPLC, SDS-PAGE). Plasminogen activator inhibitor-1 is the principal inhibitor of tissue plasminogen activator (tPA) and urokinase (uPA), the activators of plasminogen and hence fibrinolysis (the physiological breakdown of blood clots). It is a serine protease inhibitor (serpin) protein (SERPINE1). The other PAI, plasminogen activator inhibitor-2 (PAI-2) is secreted by the placenta and only present in significant amounts during pregnancy. In addition, protease nexin acts as an inhibitor of tPA and urokinase. PAI-1, however, is the main inhibitor of the plasminogen activators. Source: Recombinant protein corresponding to human PAI1, a single, non-glycosylated polypeptide chain containing 400aa (aa24-402), fused to His-tag at N-terminal, expressed in E. coli. Molecular Weight: ~45kD