[Inhibition of peroxidase oxidation of 3,3',5,5'-tetramethylbenzidine and o-phenylenediamine by 1-amino-2-naphthol-4-sulfonic acid and its polysulfide].
The kinetics of coupled peroxidation of 3,3',5,5'-tetramethylbenzidine and 1-amino-2-naphtol-4-sulfonic acid (ANSA) or its polydisulfide (poly(ADSNSA)) was studied in 0.01 M phosphate buffer (pH 6.4) at 20 degrees C. Both ANSA and poly(ADSNSA) strongly inhibited the TMB oxidation resulting in a marked delay in the product formation. Stoichiometric inhibition coefficients f, i.e., the average numbers of free-radical particles terminated by one inhibitor molecule, were estimated. The free-radical trapping effect of poly(ADSNSA) was 7.5 times greater than that of ANSA. Kinetics of coupled o-phenylenediamine (PhDA) and ANSA or poly(ADSNSA) oxidation was studied in phosphate-citrate buffers at pH 3 to 7. No lag periods in oxidation product accumulation were observed under any of the reaction conditions. A weak activation of PhDA conversion depending on pH and PhDA/ANSA ratios was observed at low ANSA concentrations, whereas increased ANSA or poly(ADSNSA) concentrations were inhibitory. The degree of PhDA inhibition was maximal in acid media, reached minimum at pH 5 to 6, and than again increased at pH above 6. Tentative mechanism of coupled aromatic amine phenol bi-substrate system peroxidation is discussed.
Karaseva
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EI
Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus 220041. ibochbel@ns.igs.ac.by
Losev
Iu P
IuP
Metelitsa
D I
DI
D000975:Antioxidants / Q000737:chemistry*; D001560:Benzidines / Q000737:chemistry*; D003864:Depression, Chemical; D005609:Free Radicals / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009284:Naphthols / Q000737:chemistry*; D010084:Oxidation-Reduction; D010655:Phenylenediamines / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013440:Sulfides / Q000737:chemistry*; D013451:Sulfonic Acids / Q000737:chemistry*
D000975:Antioxidants; D001560:Benzidines; D005609:Free Radicals; D009284:Naphthols; D010655:Phenylenediamines; D013440:Sulfides; D013451:Sulfonic Acids; C021758:3,3',5,5'-tetramethylbenzidine; C034193:1,2-diaminobenzene; D006735:Horseradish Peroxidase; C446900:1-amino-2-naphthol-4-sulfonic acid
Ingibirovanie peroksidaznogo okisleniia 3,3',5,5'-tetrametilbenzidina i o-fenilendiamina 1-amino-2-naftol-4-sul'fokislotoĭ i ee polisul'fidom.