title: Effects of enzyme/substrate ratio and of cofactors on the oxidation products of indole-3-acetic acid catalyzed by peroxidase.
abstract: During the oxidation of indole-3-acetic acid catalyzed by peroxidase, the relative amounts of the products closely depends on the enzyme/substrate ratio. In the absence of cofactors, high enzyme/substrate ratio induces a rise in the level of indole-3-aldehyde and indole-3-methanol, and a drop in that of oxindoles. 2,4-dichlorophenol, although a very efficient cofactor, promotes inhibition of the oxidation after a few minutes, presumably through the formation of a phenol-derivative inhibitor. 2-4-dichlorophenol also inhibits the production of oxindoles at all stages. Both inhibitory effects are abolished by a low concentration of enzyme. Mn2+, itself a weak inhibitor, synergizes the catalytic effect of 2,4-dichlorophenol, perhaps by preventing the formation of the inhibitor. The results are discussed against more widely accepted mechanisms of indole-3-acetic acid oxidation.
mesh_terms: D002733:Chlorophenols / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism*; D008345:Manganese / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism*
chemical_list: D002733:Chlorophenols; D007210:Indoleacetic Acids; D008345:Manganese; C030737:indoleacetic acid; D006735:Horseradish Peroxidase; D010544:Peroxidases; C004762:2,4-dichlorophenol; D010100:Oxygen