Enzymatic determination of phenols using peanut peroxidase.

The influence of phenol and its derivatives on the kinetics of oxidation of aryldiamines (indicator-substrates) catalyzed by novel plant peroxidase-cationic peanut peroxidase-was studied. The character of influence of phenols on the kinetics of enzymatic oxidation of benzidine, o-dianisidine, and 3,3',5,5'-tetramethylbenzidine (TMB) with hydrogen peroxide was found to depend on a correlation between redox properties of phenols and the indicator-substrate of peroxidase. Thus, the catalytic activity of peanut peroxidase is inhibited by phenols with redox potentials higher than that of aryldiamines mentioned above, whereas phenols with potentials below those of aryldiamines, play the role of second substrates of the enzyme. The enzymatic procedures for the determination of numerous phenols on the level of their concentrations 0.05-80 muM were developed using the reactions of benzidine, o-dianisidine, and TMB oxidation. Different analytical signals-the indicator reaction rate and the induction period duration-were used for the determination of phenols, belonging to various groups-the inhibitors and second substrates of the enzyme, respectively.