title: On the mechanism of the pseudocatalatic degradation of hydrogen peroxide by lactoperoxidase/iodide.
abstract: Hydrogen peroxide is catalytically disproportionated by lactoperoxidase in the presence of iodide ions, Km = 55 microM in 100 mM sodium phosphate, pH 7.00, 25 degrees C. Products formed are water and molecular oxygen. The reaction is competitively inhibited by hydrogen sulfite, Ki = 0.24 mM in 100 mM sodium phosphate, pH 7.00, 25 degrees C. The stoichiometry of the reaction is identical with the corresponding catalase reaction but the mechanism differs. A mechanistic model for lactoperoxidase-iodide dismutation of hydrogen peroxide is discussed.
mesh_terms: D000818:Animals; D002417:Cattle; D005260:Female; D006735:Horseradish Peroxidase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007454:Iodides / Q000378:metabolism*; D007700:Kinetics; D007784:Lactoperoxidase / Q000378:metabolism*; D008892:Milk / Q000201:enzymology; D010544:Peroxidases / Q000378:metabolism*
chemical_list: D007454:Iodides; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D007784:Lactoperoxidase; D010544:Peroxidases