The Effects of Metal Ions on Esterase Activities of Urokinase

Abstract
The esterase activity of highly purified human urokinase on Nα-acetylglycyl-L-lysine methyl ester is strongly inhibited by 1 × 10-5tol × 10“2MCu++, Hg++, Ni++, Co++, Fe+++, and Mn++ solutions, whereas Na+, K+, Ca++, and Mg++ are weakly effective. This inhibition is parallel with the inhibition of activation of plasminogen by urokinase. There is no simple linear relation between inhibition and ion concentration. Addition of ethylenediaminetetraacetate or electrodialysis fully reactivates the inhibited enzyme. These results are discussed in relation to similar effects of ions on trypsin.