title: Transition metal-catalysed oxidation of 3,3'-diaminobenzidine [DAB] in a model system.
abstract: The oxidation of 3,3'-diaminobenzidine [DAB] by H2O2 catalysed by 4 transition metals, Cu++, Co++, Fe+++ and Mn++, was investigated spectrophotometrically in a model system. The velocity of the reactions was higher with higher concentrations of DAB, H2O2 and a metal as well as with higher temperature. Optimal pH found for reactions catalysed by different transition metals was pH = 7.0 for Cu++ and Co++, pH - 6.0 for Fe+++ and pH - 9.0 for Mn++. A rapid spontaneous DAB oxidation by H2O2 in the absence of any transition metal was observed at pH less than 5.0.
mesh_terms: D015100:3,3'-Diaminobenzidine / Q000032:analysis*; D001560:Benzidines / Q000032:analysis*; D003035:Cobalt / Q000494:pharmacology; D003300:Copper / Q000494:pharmacology; D006651:Histocytochemistry; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008670:Metals / Q000494:pharmacology*; D008954:Models, Biological; D010084:Oxidation-Reduction
chemical_list: D001560:Benzidines; D008670:Metals; D015100:3,3'-Diaminobenzidine; D003035:Cobalt; D008345:Manganese; D003300:Copper; D007501:Iron