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

The effect of natural and synthetic phenolic compounds on peroxidase-c atalyzed aerobic oxidation of indole-3-acetic acid (IAA) was studied D espite the established point of view, substituted phenols are not comp etitive inhibitors of the enzyme in this reaction. Inhibition by bindi ng of the substrate to the inhibitor is also excluded. To explain the results, we suggest that under our experimental conditions the oxidati on of IAA is an enzymatic branched-chain free radical reaction and sub stituted phenols are traps of free radicals participating in this reac tion. The mechanism of inhibition by all the phenol compounds rested a ppears to be identical.