MECHANISM OF INHIBITION OF ENZYMATIC OXIDATION OF INDOLE-3-ACETIC BY PHENOLS

The effect of natural and synthetic phenolic compounds on peroxidase-catalyzed aerobic oxidation of indole-3-acetic acid (IAA) was studied Despite the established point of view, substituted phenols are not competitive inhibitors of the enzyme in this reaction. Inhibition by binding of the substrate to the inhibitor is also excluded. To explain the results, we suggest that under our experimental conditions the oxidation of IAA is an enzymatic branched-chain free radical reaction and substituted phenols are traps of free radicals participating in this reaction. The mechanism of inhibition by all the phenol compounds rested appears to be identical.