Spectroscopy methane monooxygenase

Ericson, A., Hedman, B., Green, J., Bentsen, J. G., Beer, R. H., Lippard, S. J., Dalton, H., and Hodgson, K. O., 1988, Structural characterization by EXAFS spectroscopy of the binuclear iron center in protein A of methane monooxygenase from Methylococcus capsulatus (Bath), J. Am. Chem. Soc. 110 2330n2332. 

Structure of the Iron Center Formation of the Iron Center and Tyrosyl Radical Spectroscopy of the Diferric Iron Center Spectroscopy of the Tyrosyl Radical Redox Properties of the Iron Center Mixed-Valent Form of the Iron Center Diferrous Form of the Iron Center Inhibitors to Iron-Containing Ribonucleotide Reductase Methane Monooxygenase A. Spectroscopy of the MMOH Cluster X-Ray Structure of MMOH... 

It was shown by the magnetic susceptibility measurement and Mossbauer, ESR, and UN-visible spectroscopy that TBA-I shows an antiferromagnetic coupling of the two high-spin Fe centers. For example, the 8, AEq, and J values of TBA-I, diferric complexes, oxidized methane monooxygenase (abbreviated as MMOox), and oxidized ribonucleotide reductase (abbreviated as RRox) are shown in Table 1. The 5 and AEq values for TBA-I are close to those for MMOox, 1, 2, and 4 with the symmetrical iron centers, and different from those for RRox (5 = 0.53 mms, AEqi = 1.65 mms, and 82 =... 

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. 

Biomimetic studies are currently focused on generating diiron complexes that can serve as structural and/or electronic models for oxidation states higher than Fe " that are proposed to partake in the catalytic cycles of diiron proteins such as methane monooxygenase and ribonucleotide reductase. Mossbauer spectroscopy has played a leading role in the eharacterization... 

Costas et al. have reported spectroscopic evidence for an Fe Fe complex that can be considered a structural model for the putative Fe Fe (/x-0)2 core of methane monooxygenase intermediate The synthetic complex was prepared at —80 °C in CH2CI2 by decay of a mononuclear low-spin Fe peroxo precursor. The Mossbauer spectra showed that all iron in the sample is intermediate spin (5 = 1) Fe, but the data were compatible with either a mononuclear site or a weakly coupled ( J <5cm ) symmetric dimer. Combination of the Mossbauer technique with resonance Raman and EXAFS spectroscopies provided evidence for a bis-/x-oxo bridged diiron(IV) complex. The complex of Costas et al however, is not an electronic model for intermediate Q, as the latter contains high-spin Fe sites. 

A combination of spectroscopies including Mossbauer and resonance Raman were used to identify the presence of a diiron-oxo cluster with properties similar to those identified in ribonucleotide reductase (RB2) and methane monooxygenase (MMO). These enzymes all share the ability to break unactivated carbon-hydrogen bonds with a nonheme diiron cluster cofactor. Fatty acid desaturation and methane oxidation require a two-electron reduction of the diiron cluster to initiate the oxygen activation reaction. Identification of a diiron cluster in the desaturase allowed us to propose a consensus diiron-oxo binding motif consisting of two repeats of (D/E)EXXH. 

MacArthur R, Sazinsky MH, Kuhne H, Whittington DA, Lippard SJ, Brudvig GW. 2002. Component B binding to the soluble methane monooxygenase hydroxylase by saturation-recovery EPR spectroscopy of spin-labeled MMOB. J Am Chem Soc 124(45) 13392-13393. 

WiUems J-P, Valentine AM, Gurbiel R, Lippard SJ, Hoffman BM. 1998. Small molecule binding to the mixed-valent diiron center of methane monooxygenase hydroxylase from Methylococcus capsulatus (Bath) as revealed by ENDOR spectroscopy. J Am Chem Soc 120 9410-9416. 

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