Two acyl-derivatives of urokinase, p-trimethylaminocinnamoyl-urokinase (TMA
C-Uk) and p-guanidinobenzoyl-urokinase (GB-Uk),reactivating with different
rates (k(reac) were 6 x 10(-4)/s and 6 x 10(-5)/s, respectively) were prepa
red. In comparison with free urokinase, acyl-activators were more stable in
human plasma, and their stability increased with the decrease in the react
ivation rate. Plasma clot lysis induced by all three agents was time- and d
ose-dependent, but acyl-activators caused a more prolonged fibrinolysis and
lengthened lag-phase than free urokinase. Slowly reactivating GB-Uk induce
d the most long-lasting clot lysis, whereas free urokinase was more effecti
ve for the first 3 h. A combination of GB-Uk with low dose urokinase promot
ed the long-lasting clot lysis with the shortened lag-phase.