Functional assay of plasminogen activator by hydrolysis of 14C-globin

A functional method for estimation of plasminogen activator (PA) activity is described. The end-point method follows the PA-dependent conversion of the inactive plasminogen to the potent protease plasmin. The formation of plasmin is monitored by its activity on 14C-globin to form acid-soluble radioactive products. The globinolytic assay of PA shows sensitivity similar to that of the 125I-fibrinolytic assay, and is superior in sensitivity to both the chromogenic (Pyro-Glu-Gly-Arg-pNA, S-2444) and the fluorimetric (Glu-Gly-Arg-methylcoumarin amide) methods. The assay is applicable for estimation of tissue type and urokinaselike PA activity in biologic samples, including viable cells in suspension and conditioned medium.