- A NiRhS fuel cell catalyst - lessons from hydrogenase
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We present a novel fuel cell heterogeneous catalyst based on rhodium, nickel and sulfur with power densities 5-28% that of platinum. The NiRhS heterogeneous catalyst was developedviaa homogeneous model complex of the [NiFe]hydrogenases (H2ases)
- Ogo, Seiji,Ando, Tatsuya,Minh, Le Tu Thi,Mori, Yuki,Matsumoto, Takahiro,Yatabe, Takeshi,Yoon, Ki-Seok,Sato, Yukio,Hibino, Takashi,Kaneko, Kenji
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- One Model, Two Enzymes: Activation of Hydrogen and Carbon Monoxide
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The ability to catalyze the oxidation of both H2 and CO in one reaction pot would be a major boon to hydrogen technology since CO is a consistent contaminant of H2 supplies. Here, we report just such a catalyst, with the ability to c
- Ogo, Seiji,Mori, Yuki,Ando, Tatsuya,Matsumoto, Takahiro,Yatabe, Takeshi,Yoon, Ki-Seok,Hayashi, Hideki,Asano, Masashi
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- Development of submillisecond time-resolved mass spectrometry using desorption electrospray ionization
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Reaction kinetics studied by mass spectrometry (MS) has previously been limited to millisecond time resolution. This paper presents the development of a submillisecond time-resolved mass spectrometric method for fast reaction kinetic study, based on the capability of desorption electrospray ionization (DESI) for direct and fast ionization of a high-speed liquid jet stream. The principle underlying this methodology is that two reactant solutions undergo rapid mixing to produce a free liquid jet which is ionized by DESI at different positions corresponding to different reaction times. Due to the high velocity of the liquid jet, high time resolution can be achieved. In this study, the fast reduction reaction of 2, 6-dichlorophenolindophenol (DCIP) and l-ascorbic acid (L-AA) was chosen as an example to demonstrate this concept, and the reaction rate constant was successfully measured with an unprecedented time resolution of 300 μs. The good agreement of the measured value of (116 ± 3) s -1 with that measured by the stopped-flow optical method (105 ± 2) s-1 validates the feasibility of such a DESI-MS approach. Unlike classical spectroscopic techniques that require either chromophoric substrates or labeling, MS is a general detector with high chemical specificity. Therefore, this time-resolved DESI-MS method should find wide applications in fast (bio)chemical reaction investigations.
- Miao, Zhixin,Chen, Hao,Liu, Pengyuan,Liu, Yan
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- The linkage of catalysis and regulation in enzyme action: Oxidative diversion in the hysteretically regulated yeast pyruvate decarboxylase
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The reaction catalyzed by the thiamin-diphosphate-dependent yeast pyruvate decarboxylase, which is hysteretically regulated by pyruvate, undergoes paracatalytic oxidative diversion by 2,6-dichlorophenolindophenol, which traps a carbanionic intermediate an
- Hajipour, Gholamhossein,Schowen, K. Barbara,Schowen, Richard L.
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- Crystal structure of substrate-bound bifunctional proline racemase/hydroxyproline epimerase from a hyperthermophilic archaeon
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The hypothetical OCC_00372 protein from Thermococcus litoralis is a member of the ProR superfamily from hyperthermophilic archaea and exhibits unique bifunctional proline racemase/hydroxyproline 2-epimerase activity. However, the molecular mechanism of th
- Watanabe, Yasunori,Watanabe, Seiya,Itoh, Yoshika,Watanabe, Yasuo
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- Multistage Reactive Transmission-Mode Desorption Electrospray Ionization Mass Spectrometry
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Elucidating reaction mechanisms is important for advancing many areas of science such as catalyst development. It is often difficult to probe fast reactions at ambient conditions with high temporal resolution. In addition, systems involving reagents that
- Peters, Kevin C.,Comi, Troy J.,Perry, Richard H.
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p. 1494 - 1501
(2015/08/18)
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- Type II NADH dehydrogenase of the respiratory chain of Plasmodium falciparum and its inhibitors
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Plasmodium falciparum NDH2 (pfNDH2) is a non-proton pumping, rotenone-insensitive alternative enzyme to the multi-subunit NADH:ubiquinone oxidoreductases (Complex I) of many other eukaryotes. Recombinantly expressed pfNDH2 prefers coenzyme CoQ0 as an acceptor substrate, and can also use the artificial electron acceptors, menadione and dichlorophenol-indophenol (DCIP). Previously characterized NDH2 inhibitors, dibenziodolium chloride (DPI), diphenyliodonium chloride (IDP), and 1-hydroxy-2-dodecyl-4(1H)quinolone (HDQ) do not inhibit pfNDH2 activity. Here, we provide evidence that HDQ likely targets another P. falciparum mitochondrial enzyme, dihydroorotate dehydrogenase (pfDHOD), which is essential for de novo pyrimidine biosynthesis.
- Dong, Carolyn K.,Patel, Vishal,Yang, Jimmy C.,Dvorin, Jeffrey D.,Duraisingh, Manoj T.,Clardy, Jon,Wirth, Dyann F.
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supporting information; experimental part
p. 972 - 975
(2009/08/15)
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- Prevalence of thermodynamic control in the reaction of thiosulphate ion with 2,6-dichlorophenolindophenol in phosphate buffer
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The interaction of thiosulphate ion (TS) with 2, 6-dichlorophenolindophenol (In) has been investigated kinetically in phosphate buffer and tetrathionate has been detected as the oxidation product.The reaction is first order in TS while the order in In cha
- Saxena, Deepali,Mishra, K. K.
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p. 576 - 579
(2007/10/02)
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- Kinetics and Mechanism of the Oxidation of 1-Dodecanethiol by 2.6-Dichlorophenolindophenol (a Coenzyme Q Model) in Aqueous-Acetone Medium
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The oxidation kinetics of 1-dodecanethiol by 2.6-dichlorophenolindophenol in aqueous acetone medium and in presence of hydroxyl ions have been studied colorimetrically.The reaction follows a first order kinetics in each principal reactant.The increase in hydroxyl ion concentration decreases the rate in a complex manner.The addition of reaction products does not affect the rate but a slight variation is noticed on increasing the ionic strenght of the system.The rate increases on increasing the dielectric constant of the medium.The reaction was studied at differenttemperatures and activation parameters were evaluated.A suitable mechanism consistent with the kinetic data has been proposed which leads to the following rate expression: .
- Kashyap, M.,Mishra, K. K.
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p. 331 - 339
(2007/10/02)
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- KINETICS AND MECHANISM OF THE OXIDATION OF 1-PROPANETHIOL AND 2-PROPANETHIOL BY 2,6-DICHLOROPHENOLINDOPHENOL IN METHANOL-WATER MEDIUM
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The oxidative cleavage of 1-propanethiol and 2-propanethiol (1-PT and 2-PT respectively) by 2,6-dichlorophenolindophenol have been studied in methanol-water medium and the thiol-disulphide conversion has been studied kinetically in presence of hydroxyl ion at 30 deg C.The reaction follows a second order kinetics in indophenol in both cases.The order of reaction is one in 1-propanethiol while in 2-propanethiol, the order shows a transition from zero to one at higher concentrations of alkali.The rate constant shows a direct proportionality with -> in case of 1-propanethiol but in the oxidation of 2-propanethiol, an inverse linear proportionality has been noticed.Again in the oxidation of 2-PT, the rate is indifferent to -> at higher concentrations of sodium hydroxide (ca. > 2.5 * 10-4 M).The rate of oxidation of 1-PT increases on increasing the dielectric constant of the medium while a decrease in the rate of oxidation of 2-PT has been observed in these studies.Variation of ionic strength and the addition of reaction products do not influence the rate in both the cases.The reaction has been studied at different temperatures and activation parameters have been evaluated.Mechanisms consistent with kinetic data have been proposed and the diversity in kinetic results has been interpreted in terms of the difference in the mode of addition of thiol molecule to indophenol dimer.
- Pandey, N. K.,Mishra, K. K.,Kashyap, (Ku.) M.
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p. 179 - 188
(2007/10/02)
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