plasminogen (plaz-min-ŏ-jĕn) n. a substance normally present in the blood plasma that may be activated to form plasmin. See fibrinolysis. p. activator any enzyme that converts plasminogen to plasmin, of which there are two types: tissue-type plasminogen activator and urokinase-like plasminogen activator.

plasminogen The inactive precursor of the enzyme plasmin. Plasminogen is incorporated into blood clots and is converted to plasmin during fibrinolysis.