title: Catalytic Formation of Hydrogen Peroxide from Coenzyme NADH and Dioxygen with a Water-Soluble Iridium Complex and a Ubiquinone Coenzyme Analogue.
abstract: A ubiquinone coenzyme analogue (Q0: 2,3-dimethoxy-5-methyl-1,4-benzoquinone) was reduced by coenzyme NADH to yield the corresponding reduced form of Q0 (Q0H2) in the presence of a catalytic amount of a [C,N] cyclometalated organoiridium complex (1: [Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))benzoic acid-κC(3))(H2O)]2SO4) in water at ambient temperature as observed in the respiratory chain complex I (Complex I). In the catalytic cycle, the reduction of 1 by NADH produces the corresponding iridium hydride complex that in turn reduces Q0 to produce Q0H2. Q0H2 reduced dioxygen to yield hydrogen peroxide (H2O2) under slightly basic conditions. Catalytic generation of H2O2 was made possible in the reaction of O2 with NADH as the functional expression of NADH oxidase in white blood cells utilizing the redox cycle of Q0 as well as 1 for the first time in a nonenzymatic homogeneous reaction system.
authors.affiliation: Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology , Suita, Osaka 565-0871, Japan.
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Suenobu
authors.affiliation: Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology , Suita, Osaka 565-0871, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Shibata
authors.affiliation: Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology , Suita, Osaka 565-0871, Japan.|Department of Chemistry and Nano Science, Ewha Womans University , Seoul 120-750, Korea.|Faculty of Science and Engineering, Meijo University, ALCA and SENTAN, Japan Science and Technology Agency , Nagoya, Aichi 468-0073, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Fukuzumi
mesh_terms: D016227:Benzoquinones / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007495:Iridium / Q000737:chemistry*; D009243:NAD / Q000737:chemistry* / Q000378:metabolism; D010100:Oxygen / Q000737:chemistry*; D012995:Solubility; D013696:Temperature; D014867:Water
chemical_list: D016227:Benzoquinones; D056831:Coordination Complexes; D014867:Water; D009243:NAD; D007495:Iridium; C109863:ubiquinone-O; D006861:Hydrogen Peroxide; D010100:Oxygen