Measurement of NQO2 Catalytic Activity and of Its Inhibition by Melatonin.

ABSTRACT

The third melatonin binding site MT3 turned out to be an enzyme, NQO2 (E.C. 1.6.99.2). Its catalytic activity is inhibited by melatonin with an IC50 in the 50-100 µM range. Some of the functions of melatonin at pharmacological concentrations (1 µM and above) might be explained by this inhibition capacity of melatonin at NQO2. In order to determine precisely these parameters, it is required to comprehend the basic enzymology of this enzyme. In the following chapter, we present the basic conditions of measuring NQO2 catalytic activities and inhibition.