The Use of N-ethyl-urethan in Plasma Plasminogen Assay

In optimal concentration, N-ethyl-urethan enhances urokinase-induced caseinolytic activity in human plasma mainly through an irreversible denaturation of inhibitors and more effectively than o-thymotic-acid-Na. In estimation of plasminogen-plasmin in human plasma, the use of N-ethyl-urethan was found to be a simpler means of denaturating inhibitors than acidification, but only partial removal of inhibitory activity was obtained. Because the presence of casein protects against the loss of proteolytic capacity in plasma, N-ethyl-urethan should be mixed with the casein and not directly with the plasma.