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Methane monooxygenase belongs to the class of oxidoreductase enzymes (EC 1.14.13.25). There are two forms of MMO: the well-studied soluble form (sMMO) and the particulate form (pMMO). [2] The active site in sMMO contains a di-iron center bridged by an oxygen atom (Fe-O-Fe), whereas the active site in pMMO utilizes copper.
Cells containing pMMO have demonstrated higher growth capabilities and higher affinity for methane than sMMO containing cells. [7] It is suspected that copper ions may play a key role in both pMMO regulation and the enzyme catalysis, thus limiting pMMO cells to more copper-rich environments than sMMO producing cells. [30]
The overall reactions are: CH 4 + 4 NO 3 − → CO 2 + 4 NO 2 − + 2 H 2 O 3 CH 4 + 8 NO 2 − + 8 H + → 3 CO 2 + 4 N 2 + 10 H 2 O. ANME-2d is shown to be responsible nitrate-driven AOM. [5] The ANME-2d, named Methanoperedens nitroreducens, is able to perform nitrate-driven AOM without a partner organism via reverse methanogenesis with nitrate as the terminal electron acceptor, using genes ...
It is thought to be secreted to the extracellular media to recruit copper, a critical component of methane monooxygenase, the first enzyme in the series that catalyzes the oxidation of methane into methanol. Methanobactin functions as a chalkophore, similar to iron siderophores, by binding to Cu(II) or Cu(I) then shuttling the copper into the cell
the reaction steps presented here are just a part of the reaction sequence, see reference for more details. Photocatalytic oxidation with TiO 2: [15] TiO 2 + UV → e − + h + (irradiation of the photocatalytic surface leads to an excited electron (e −) and electron gap (h +)) Ti(IV) + H 2 O ⇌ Ti(IV)-H 2 O (water adsorbs onto the catalyst ...
Of the two half reactions, the oxidation step is the most demanding because it requires the coupling of 4 electron and proton transfers and the formation of an oxygen-oxygen bond. This process occurs naturally in plants photosystem II to provide protons and electrons for the photosynthesis process and release oxygen to the atmosphere, [ 1 ] as ...
Some organisms can oxidize methane, functionally reversing the process of methanogenesis, also referred to as the anaerobic oxidation of methane (AOM). Organisms performing AOM have been found in multiple marine and freshwater environments including methane seeps, hydrothermal vents, coastal sediments and sulfate-methane transition zones. [ 8 ]
The free radicals generated by this process engage in secondary reactions. For example, the hydroxyl is a powerful, non-selective oxidant. [6] Oxidation of an organic compound by Fenton's reagent is rapid and exothermic and results in the oxidation of contaminants to primarily carbon dioxide and water.