Kinetic study of urease‐catalysed urea hydrolysis

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Abstract
The kinetics of the urease‐catalysed hydrolysis of urea in phosphate and citrate buffers have been studied. The effects of urease concentration, substrate concentration, pH and temperature of solutions, and particularly the concentrations of buffers and product on the reaction rate of urea hydrolysis have been examined. The activation energies in two buffer systems indicate that the reaction mechanism catalysed by urease may be the same in each case. A substrate inhibition model has been developed that describes the effect of substrate concentration ranging from 0.001 to 4 mol dm−3. The experimental data indicated that the inhibition of urease by phosphate is of partially mixed type, whilst that by citrate is uncompetitive. In contrast ammonium ions exhibited no significant influence on the rate of urea hydrolysis by urease.