title: Efficient catalytic interconversion between NADH and NAD+ accompanied by generation and consumption of hydrogen with a water-soluble iridium complex at ambient pressure and temperature.
abstract: Regioselective hydrogenation of the oxidized form of β-nicotinamide adenine dinucleotide (NAD(+)) to the reduced form (NADH) with hydrogen (H(2)) has successfully been achieved in the presence of a catalytic amount of a [C,N] cyclometalated organoiridium complex [Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))benzoic acid-κC(3))(H(2)O)](2) SO(4) [1](2)·SO(4) under an atmospheric pressure of H(2) at room temperature in weakly basic water. The structure of the corresponding benzoate complex Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))-benzoate-κC(3))(H(2)O) 2 has been revealed by X-ray single-crystal structure analysis. The corresponding iridium hydride complex formed under an atmospheric pressure of H(2) undergoes the 1,4-selective hydrogenation of NAD(+) to form 1,4-NADH. On the other hand, in weakly acidic water the complex 1 was found to catalyze the hydrogen evolution from NADH to produce NAD(+) without photoirradiation at room temperature. NAD(+) exhibited an inhibitory behavior in both catalytic hydrogenation of NAD(+) with H(2) and H(2) evolution from NADH due to the binding of NAD(+) to the catalyst. The overall catalytic mechanism of interconversion between NADH and NAD(+) accompanied by generation and consumption of H(2) was revealed on the basis of the kinetic analysis and detection of the catalytic intermediates.
authors: Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan.
authors: Yuta
authors: Y
authors: Maenaka
authors: Tomoyoshi
authors: T
authors: Suenobu
authors: Shunichi
authors: S
authors: Fukuzumi
mesh_terms: D040761:Biomimetic Materials / Q000138:chemical synthesis / Q000737:chemistry; D002384:Catalysis; D006859:Hydrogen / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006864:Hydrogenase / Q000378:metabolism; D007495:Iridium / Q000737:chemistry*; D008024:Ligands; D009243:NAD / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D011312:Pressure; D012995:Solubility; D013237:Stereoisomerism; D013379:Substrate Specificity; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D014867:Water; D009243:NAD; D007495:Iridium; D006859:Hydrogen; D006864:Hydrogenase