Inhibition of peroxidase-catalyzed oxidation of 3,3 ,5,5 -tetramethylbenzidine by aminophenols

Peroxidase-catalyzed oxidation of 3,3 ,5,5 -tetramethylbenzidine (TMB) was inhibited by o-aminophenol (AP), 2-amino-4-tert-butylphenol (ATBP), 2-amino-4,6-di-tert-butylphenol (ADTBP), and 4-tert-butylpyrocatechol (TBP). Inhibitors were characterized by inhibition constant K(i) and stoichiometric coe...

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Bibliographic Details
Published in:Biochemistry (Moscow) 2005-03, Vol.70 (3), p.322-329
Main Authors: Naumchik, I V, Karasyova, E I, Metelitza, D I, Edimecheva, I P, Sorokin, V L, Shadyro, O I
Format: Article
Language:English
Subjects:
Amines
Aminophenols - pharmacology
Antioxidants - analysis
Benzidines - metabolism
Biochemistry
Catechols - pharmacology
Chromatography
Chromatography, Gas
Horse-radish
Horseradish Peroxidase - antagonists & inhibitors
Kinetics
Liquid chromatography
Metalloenzymes
Oxidation
Oxidation-Reduction - drug effects
Phenols
Stoichiometry
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Summary:Peroxidase-catalyzed oxidation of 3,3 ,5,5 -tetramethylbenzidine (TMB) was inhibited by o-aminophenol (AP), 2-amino-4-tert-butylphenol (ATBP), 2-amino-4,6-di-tert-butylphenol (ADTBP), and 4-tert-butylpyrocatechol (TBP). Inhibitors were characterized by inhibition constant K(i) and stoichiometric coefficient f, the number of radicals terminated by one inhibitor molecule. The most efficient inhibitor is ADTBP characterized by K(i) = 36 microM in 0.015 M phosphate citrate buffer, pH 6.0, at 20 degrees C. According to their antiradical efficiency, the studied inhibitors can be arranged as follows: ADTBP > ATBP > AP > TBP. The role of the NH(2) group in the inhibitory capacity of aminophenols is discussed. Using gas-liquid chromatography, kinetics of consumption of the initial components and accumulation of the reaction products on peroxidase-catalyzed oxidation of the TMB-TBP pair was studied; the data clarify the stages of a complex process of co-oxidation of amines and phenols.
ISSN:0006-2979
1608-3040
DOI:10.1007/s10541-005-0118-z