Methane monooxygenase reduced

Methane monooxygenase is a classic monooxygenase in which two reducing equivalents from NAD(P)H are utilized to split the O—O bond of O2. Later, one oxygen atom is reduced to water while the second oxygen atom is incorporated into the substrate to yield methanol [42-45],... 

Figure 1. Characteristic EPR signals of Fe(II)Fe(III) sites in semimethemerythrinj (a), semimethemerythrinQ (b), reduced uteroferrin (c), reduced uteroferrin-molybdate complex (d), reduced bovine spleen purple acid phosphatase (e), reduced component A of methane monooxygenase (f). (Reproduced with permission from ref. 26. Copyright 1987 Elsevier.)...

Proteins with dinuclear iron centres comprise some well studied representatives like ribonucleotide reductase (RNR), purple acid phosphatase (PAP), methane monooxygenase hydroxylase (MMOH), ruberythrin and hemerythrin. The latter is an oxygen carrier in some sea worms it has been first characterized within this group and has thus laid the foundation to this class of iron coordination motif. Ruberythrin is found in anaerobic sulfate-reducing bacteria. Its name implies that, in addition to a hemerythrin-related diiron site another iron is coordinated in a mononuclear fashion relating to rubredoxin which is an iron-... 

Chang, S-L., Wallar, B.J., Lipscomb, J.D., and Mayo, K.H. (2001) Residues in Methylosinus trichosporium OB3b methane monooxygenase component B involved in molecular interactions with reduced- and oxidized-hydroxylase component A role for the N-terminus, Biochemistry 40, 9539-9551. 

Davydov, R., Valentine, A. M., Komar-Panicucci, S., Hoffman, B. M., and Lippard, S. J., 1999, An EPR study of the dinuclear iron site in the soluble methane monooxygenase from Methylococcus capsulatus (Bath) reduced by one electron at 77K the effects of component interactions and the binding of small molecules to the diiron(lll) center. Biochemistry 38 418864197. 

Liu, K. E., Wang, D., Huynh, B. H., Edmondson, D. E., Salifoglou, A., and Lippard, S. J., 1994, Spectroscopic detection of intermediates in the reaction of dioxygen with the reduced methane monooxygenase hydroxylase from Methylococcus capsulatus (Bath), J. Am. Chem. Soc. 116 7465n7466. 

Pulver, S., Proland, W. A., Pox, B. G., Lipscomb, J. D., and Solomon, E. 1., 1993, Spectroscopic studies of the coupled binuclear non-heme iron active site in the fully reduced hydroxylase component of methane monooxygenase Comparison to deoxy and deoxy-azide hemerythrin, J. Am. Chem. Soc. 115 12409912422. 

To understand the role of these bacteria in methane cycling, the methane oxidation system must be studied. In methanotrophs, methane is oxidized to methanol by an enzyme called the methane monooxygenase (MMO) (I), which uses methane, molecular oxygen, and reducing equivalents to produce methanol and water. All known methanotrophs contain a membrane-bound MMO, called the particulate methane monooxygenase (pMMO). The presence of this enzyme system is correlated with the complex internal membrane system found in all known methanotrophs. 

ACP = acyl carrier protein ACPA D = ACPA desat-urase AlkB = octane 1-monooxygenase AOX = alternative oxidase DMQ hydroxylase = 5-demethoxyquinone hydroxylase EXAFS = extended X-ray absorption fine structure spectroscopy FMN = flavin mononucleotide FprA = flavoprotein A (flavo-diiron enzyme homologue) Hr = hemerythrin MCD = magnetic circular dichroism MME hydroxylase = Mg-protophorphyrin IX monomethyl ester hydroxylase MMO = methane monooxygenase MMOH = hydroxylase component of MMO NADH = reduced nicotinamide adenine dinucleotide PAPs = purple acid phosphatases PCET = proton-coupled electron transfer, PTOX = plastid terminal oxidase R2 = ribonucleotide reductase R2 subunit Rbr = rubrerythrin RFQ = rapid freeze-quench RNR = ribonucleotide reductase ROO = rubredoxin oxygen oxidoreductase XylM = xylene monooxygenase. 

---