title: Inhibition of the Fenton reaction by nitrogen monoxide.
abstract: The toxicity of iron is believed to originate from the Fenton reaction which produces the hydroxyl radical and/or oxoiron2+. The effect of nitrogen monoxide on the kinetics of the reaction of iron(II) bound to citrate, ethylenediamine-N,N'-diacetate (edda), ethylenediamine-N,N,N',N'-tetraacetate (edta), (N-hydroxyethyl)amine-N,N',N'-triacetate (hedta), and nitrilotriacetate (nta) with hydrogen peroxide was studied by stopped-flow spectrophotometry. Nitrogen monoxide inhibits the Fenton reaction to a large extent. For instance, hydrogen peroxide oxidizes iron(II) citrate with a rate constant of 5.8x10(3) M(-1) s(-1), but in the presence of nitrogen monoxide, the rate constant is 2.9x10(2) M(-1) s(-1) . Similar to hydrogen peroxide, the reaction of tert-butyl hydroperoxide with iron(II) complexes is also efficiently inhibited by nitrogen monoxide. Generally, nitrogen monoxide binds rapidly to a coordination site of iron(II) occupied by water. The rate of oxidation is influenced by the rate of dissociation of the nitrogen monoxide from iron(II).
authors.affiliation: Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Hönggerberg, Wolfgang-Pauli-Strasse 10, 8093, Zurich, Switzerland.
authors.forename: Changyuan
authors.initials: C
authors.lastname: Lu
authors.forename: Willem H
authors.initials: WH
authors.lastname: Koppenol
mesh_terms: D003198:Computer Simulation; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D008054:Lipid Peroxides / Q000737:chemistry; D009569:Nitric Oxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet
chemical_list: D008054:Lipid Peroxides; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D007501:Iron