Fig. 7

a Thiol influence on urease inactivation by ASB relative to the control activity. The percent of the enzyme activity in the presence of ASB without the thiol is given as comparison. Concentration of the thiol: L-cys, DTT, and ASB were 4 mM. Enzyme activity was determined after 10, 30, 60 min of incubation; b Influence of thiol order of components preincubation on urease inactivation by ASB. The initial 20 min preincubation mixture contained components given in brackets. The preincubation was continued the further 20 min after addition of the last component (component given outside for brackets). The final preincubation mixtures contained 0.25 mg/mL urease, 20 mM phosphate buffer, pH 7.0, 2 mM EDTA, 4 mM ASB, and DTT or L-cys. Enzyme activity was determined after 40 min of preincubation time. The percent of the enzyme activity in the presence of ASB without the thiol is given for comparison