Effect of cadmium on kinetic characteristics of soil urease.

The kinetic characteristics of soil urease were studied.The results showed that soil urease was remarkable inhibited with the concentration of Cd adding.While the maximum inhibtion ratio was attained in the sixth incubation day,the relationship between the concentration of Cd2+ and soil urease was described by two models,and the model y=c(1+ax)/(1+bx) was more suitable.This means that the inhibtion of Cd on soil urease was part of inhibition.The Km was not effected,but the Vmax and Vmax/Km were lowed while Cd adding.This results showed that the enzymatic reaction mechanism was noncompetion-inhibitory between soil urease and cadmium.