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 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.

Inhibition of soybean urease by triketone oximes.

Competitive inhibition of soybean urease by 15 triketone oximes has been studied at 36 degrees C in aqueous solution (pH 4.95). The studied oximes are supposed chelators for the nickel atom in the urease metallocenter.

Peroxidase-catalyzed co-oxidation of 3,3',5,5'-tetramethylbenzidine in the presence of substituted phenols and their polydisulfides.

The steady-state kinetics of the horseradish peroxidase (HRP)-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) has been studied in the presence of 2-amino-4-nitrophenol (ANP), gallic acid (GA) or 4,4'-dihydroxydiphenylsulfone (DDS) and their polydisulfides poly(ADSNP), poly(DSGA), poly(DSDDS) at 20 degrees C in 10 mM phosphate buffer, pH 6.4, supplemented with 5-10% dimethylformamide. The second-order rate constants for the reactions of ANP, GA, poly(DSGA) and poly(DSDDS) with HRP-Compound I (k2) and Compound II (k3) have been determined at 25 degrees C in 10 mM phosphate buffer, pH 6.

Activation of peroxidase-catalyzed oxidation of aromatic amines with 2-aminothiazole and melamine.

The peroxidase-catalyzed oxidation of 3,3;,5,5;-tetramethylbenzidine (TMB), ortho-phenylenediamine (PDA), and 5-aminosalicylic acid (5-ASA) is significantly accelerated in the presence of 2-aminothiazole (AT) and melamine (MA), and an increase in their concentrations is associated with a parallel increase in the k(cat) and K(m) values for TMB and PDA. The activation of the peroxidase-catalyzed oxidation of TMB and PDA is quantitatively characterized by a coefficient (degree) alpha (M(-1)) which significantly depends on pH in the range 6.2-6.

Activation of peroxidase-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine with poly(salicylic acid 5-aminodisulfide).

5-Aminosalicylic acid (5-ASA) inhibited by a mixed mechanism the peroxidase catalyzed oxidation of tetramethylbenzidine (TMB) in 0.015 M phosphate-citrate buffer (pH 6.4) supplemented with 5% DMSO and 5% DMF.