Competitive inhibition by hydrogen peroxide produced in glucose oxidation catalyzed by glucose oxidase

In our previous paper, the glucose oxidation catalyzed by the immobilized glucose oxidase was found to be competitively inhibited by hydrogen peroxide produced, and the inhibition constant K-I was determined to be almost equal to the apparent Michaelis constant with respect to oxygen K-M. In the present study, the value of K-I has been determined in the late stage of the free glucose oxidase catalyzed reaction with an appreciable amount of hydrogen peroxide produced. The K-I value has been found also to be almost equal to the K-M value, which agrees with the result of the previous paper. Furthermore, the kinetic data obtained with too high concentrations of hydrogen peroxide added initially have been shown to give the same values of K-M and K-I as determined above. Finally, such a finding as an approximate equality of K-I to K-M has suggested that the reduced form of glucose oxidase has almost the same affinity to hydrogen peroxide as that to oxygen. (C) 2002 Elsevier Science B.V. All rights reserved.