u-plasminogen activator


activator

 [ak´tĭ-va″ter] a substance that makes another substance active or reactive, induces a chemical reaction, or combines with an enzyme to increase its catalytic activity.plasminogen activator a substance that activates plasminogen and converts it into plasmin; see activator" >t-plasminogen activator and activator" >u-plasminogen activator.tissue plasminogen activator (TPA, t-PA) (t-plasminogen activator) a serine endopeptidase synthesized by endothelial cells, the major physiologic activator of plasminogen; when bound to fibrin clots it catalyzes the conversion of plasminogen to plasmin by hydrolysis of a specific arginine-valine bond. It can be produced by recombinant technology for use in therapy" >thrombolytic therapy. It acts directly on blood clots and therefore presents a small risk of systemic bleeding; occasionally allergic reactions may occur.u-plasminogen activator (urinary plasminogen activator) a serine endopeptidase that acts as a plasminogen activator by catalyzing the preferential cleavage of plasminogen at the same arginine-valine bond where activator" >t-plasminogen activator cleaves. It is produced in the kidney and excreted in the urine and is used in therapy" >thrombolytic therapy (when used as a pharmaceutical, it is usually called urokinase). Unlike t-plasminogen activator or prourokinase, it does not require fibrin for activity. Called also urokinase.