Summary
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.
