Oxidation of methane to methanol by hydrogen peroxide on a supported hematin catalyst

Nagiev, T. M.; Abbasova, M. T.

doi:10.1016/s0167-2991(00)80621-7

Cited by 4 publications

(7 citation statements)

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“…Previous data have led to the conclusion that the species responsible for oxygenation of substrate is the diferryl intermediate Q, which forms after intermediate P during single‐turnover kinetics [15,16]. As, under appropriate conditions, hydrogen peroxide is known to oxidize methane directly to form methanol [17], the data presented here permit the alternative conclusion that intermediate Q may be the result of a side reaction and hydrogen peroxide per se is effecting the oxidation of substrate. Indeed the reactivity of hydrogen peroxide may well be far greater in its nonaquated form within the highly hydrophobic pocket adjacent to the binuclear iron centre [2,18] than aquated hydrogen peroxide in the bulk solution.…”

Section: Discussionmentioning

confidence: 65%

Cofactor‐independent oxygenation reactions catalyzed by soluble methane monooxygenase at the surface of a modified gold electrode

Astier

Balendra

Hill

et al. 2003

European Journal of Biochemistry

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Soluble methane monooxygenase (sMMO) is a three-component enzyme that catalyses dioxygen-and NAD(P)Hdependent oxygenation of methane and numerous other substrates. Oxygenation occurs at the binuclear iron active centre in the hydroxylase component (MMOH), to which electrons are passed from NAD(P)H via the reductase component (MMOR), along a pathway that is facilitated and controlled by the third component, protein B (MMOB). We previously demonstrated that electrons could be passed to MMOH from a hexapeptide-modified gold electrode and thus cyclic voltammetry could be used to measure the redox potentials of the MMOH active site. Here we have shown that the reduction current is enhanced by the presence of catalase or if the reaction is performed in a flow-cell, probably because oxygen is reduced to hydrogen peroxide, by MMOH at the electrode surface and the hydrogen peroxide then inactivates the enzyme unless removed by catalase or a continuous flow of solution. Hydrogen peroxide production appears to be inhibited by MMOB, suggesting that MMOB is controlling the flow of electrons to MMOH as it does in the presence of MMOR and NAD(P)H. Most importantly, in the presence of MMOB and catalase, the electrode-associated MMOH oxygenates acetonitrile to cyanoaldehyde and methane to methanol. Thus the electochemically driven sMMO showed the same catalytic activity and regulation by MMOB as the natural NAD(P)H-driven reaction and may have the potential for development into an economic, NAD(P)H-independent oxygenation catalyst. The significance of the production of hydrogen peroxide, which is not usually observed with the NAD(P)H-driven system, is also discussed.Keywords: electrochemical oxygenation; regulatory protein; soluble methane monooxygenase.Soluble methane monooxygenase (sMMO) catalyses the bacterial oxidation of methane to methanol using NAD(P)H as cofactor [1]. sMMO consists of three components: the hydroxylase (MMOH), the reductase (MMOR) and a regulatory protein (known as MMOB or protein B). The active site of the enzyme is located on the a subunit of MMOH and consists of a binuclear iron species located in a hydrophobic pocket approximately 12 Å beneath the protein surface [2]. MMOH, which has an (abc) 2 quaternary structure, interacts with the MMOR component from which it receives reductant to drive the reaction [3]:The regulatory protein (MMOB) plays several roles in the catalytic process including modulating the rate of electron transfer between MMOR and MMOH [4,5], altering the redox potential of the binuclear iron site [6], optimizing the interaction between MMOR and MMOH [7], controlling the access of large substrates to the active site [8] and affecting the regioselectivity of substrate oxygenation [9,10]. The 15.9-kDa MMOB also exists in a naturally occurring truncated form in which 12 amino acids are lost from the N-terminus. This truncated form (MMOB tru ) is completely inactive within the sMMO complex [11]. The sMMO reaction can also be driven using hydrogen peroxide via the peroxide shunt reaction [...

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Section: Discussionmentioning

confidence: 65%

Cofactor‐independent oxygenation reactions catalyzed by soluble methane monooxygenase at the surface of a modified gold electrode

Astier

Balendra

Hill

et al. 2003

European Journal of Biochemistry

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“…Monooxigenase reaction for synthesizing methanol from methane was studied in the presence of cytochrome P-450 biosimulators, such as ferroprotoporphyrin catalysts with the carriers (A1 2 O 3 , NaX, aluminum-chromiumsilicate and aluminum-magnesium-silicate). This reaction helped in the detection of the highest catalytic activity for PPFe 3+ OH/aluminum-magnesium-silicate [11], which also displayed the highest catalytic activity for hydroxylation reaction. As shown, optimal hydroxylic activity of the catalyst is displayed in the initial 30 min of its operation (methanol output equals 60 wt%, selectivity is 97 wt%).…”

Section: Interference Of Hydrogen Peroxide Dissociation and Substratementioning

confidence: 93%

“…As is clear from schemes (11) and (12), only two substances formally participate in such a system of conjugated reactions.…”

Section: Three-component Conjugated Processesmentioning

confidence: 99%

“…and under the condition that the actor is completely spent for target product formation only according to schemes (11) and (12), the equation: The higher the effectiveness of intermediate substance catalytic action on the secondary reaction or chain transformation of the substrate, the higher is the D value.…”

Section: If 2mentioning

confidence: 99%

“…Note also that some authors [11]- [14] have had to use all their inventiveness in order to impart high experimental demonstrativeness to chemical interference.…”

Section: Interference Of Hydrogen Peroxide Dissociation and Substratementioning

confidence: 99%

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The Theory of Coherent Synchronized Reactions: Chemical Interference Logics

Nagiev¹

2015

MSA

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Various types of possible interactions between reactions are discussed. Some of them are united by the general idea of chemical reaction interference. The ideas on conjugated reactions are broadened and the determinant formula is deduced; the coherence condition for chemical interference is formulated and associated phase shifts are determined. It is shown how interaction between reactions may be qualitatively and quantitatively assessed and kinetic analysis of complex reactions with under researched mechanisms may be performed with simultaneous consideration of the stationary concentration method. Using particular examples, interference of hydrogen peroxide dissociation and oxidation of substrates is considered. Therefore macrokinetic theory of coherent synchronized reactions is offered.

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Coherently synchronized reaction of methane oxidation by green oxidizer–hydrogen peroxide – over the biomimetic catalyst iron pentafluorotetraphenylporphyrin deposited on alumina

Nahmatova

Gasanova

Vodyankina

et al. 2022

Reac Kinet Mech Cat

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The activity of penta- FTPhPFe(III)/Al2O3 biomimetic catalyst in the reaction of methane direct conversion into methanol by green oxidant hydrogen peroxide was studied at T = 150–350 °C and atmospheric pressure, where methanol yield was 19.2% with methane conversion of 28%. Based on the results of the structural analysis of the Al2O3 support and the biomimetic catalyst sample the mesoporosity of support with pore size in the range of dp = 2.4–22.2 nm in the cylindric shape with an open end and the synthesized biomimetic nanostructure were determined. The data on the definition of the nature and quantitative assessment of Al2O3 support acid–base centers are given that made possible to describe probable mechanism of methane coherent-synchronized oxidation into methanol on the biomimetic.

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Oxidation of methane to methanol by hydrogen peroxide on a supported hematin catalyst

Cited by 4 publications

References 0 publications

Cofactor‐independent oxygenation reactions catalyzed by soluble methane monooxygenase at the surface of a modified gold electrode

Cofactor‐independent oxygenation reactions catalyzed by soluble methane monooxygenase at the surface of a modified gold electrode

The Theory of Coherent Synchronized Reactions: Chemical Interference Logics

Coherently synchronized reaction of methane oxidation by green oxidizer–hydrogen peroxide – over the biomimetic catalyst iron pentafluorotetraphenylporphyrin deposited on alumina

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