title: Mechanism studies of enzymatically formed tolidine blue and determination of peroxidatic activities.
abstract: In aqueous solution peroxidase catalyzes the conversion of o-tolidine to tolidine blue by hydrogen peroxide. This reaction of practical significance for analytical tests was studied by optical and ESR spectroscopy. For the blue dye formed in aqueous solution a meriquinoidic structure was proposed which is in equilibrium with an instable radical compound. This equilibrium is shifted to higher radical concentrations by ethylene glycol. Naphthene derivatives stabilize the meriquinoidic structure by means of non-covalent interactions resulting in a decrease of the radical concentration. In crosslinked gelatin the dye formation runs analogously, so that this system is suitable for providing evidence for H2O2-forming reactions. Naphthene derivatives substituted by sufficiently long aliphatic groups are diffusion stable in crosslinked gelatin. By interacting with the dye they prevent its rapid chemical decomposition and diffusion into the sample solution. It was shown, furthermore, that by means of such systems with a suitable structure of the layers both substrates and enzymes participating in the reaction may be determined analytically. This does provide a basis for developing new analytical test variants.
mesh_terms: D001560:Benzidines / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D005949:Glucose Oxidase / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism*; D006861:Hydrogen Peroxide; D007202:Indicators and Reagents; D010544:Peroxidases / Q000378:metabolism*
chemical_list: D001560:Benzidines; D007202:Indicators and Reagents; C009501:2-tolidine; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; D006735:Horseradish Peroxidase; D010544:Peroxidases