title: Mechanism of horseradish peroxidase-catalyzed oxidation of malonaldehyde.
abstract: The mechanism of malonaldehyde oxidation by horseradish peroxidase in the presence of manganese(II) and acetate was investigated. Our results show that an apparent oxygenase behavior demonstrated by peroxidase in this system can be explained in terms of normal peroxidase activity. A free radical is generated from the reaction of malonaldehyde with compounds I and II of peroxidase; this radical is scavenged by dissolved molecular oxygen to give the appearance of peroxidase acting as an oxygenase. Oxygen consumption, absorbance spectra, and kinetic results show that the reaction is initiated by autoxidation of malonaldehyde to give a free radical. The radical reacts with oxygen and through the action of manganese(II), a peroxide is generated. This peroxide drives the peroxidase cycle to generate more free radicals which propagate the oxygen consumption reaction.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, Canada.
authors.forename: I D
authors.initials: ID
authors.lastname: MacDonald
authors.forename: H B
authors.initials: HB
authors.lastname: Dunford
mesh_terms: D000085:Acetates / Q000494:pharmacology; D019342:Acetic Acid; D002384:Catalysis; D005609:Free Radicals; D006735:Horseradish Peroxidase / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008314:Malonates / Q000378:metabolism*; D008315:Malondialdehyde / Q000378:metabolism*; D008345:Manganese / Q000494:pharmacology; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010544:Peroxidases / Q000378:metabolism*; D013053:Spectrophotometry
chemical_list: D000085:Acetates; D005609:Free Radicals; D008314:Malonates; D008345:Manganese; D008315:Malondialdehyde; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D010544:Peroxidases; D019342:Acetic Acid