@article {592,
	title = {Isolation and characterization of a soluble NADPH-dependent Fe(III) reductase from Geobacter sulfurreducens.},
	journal = {J Bacteriol},
	volume = {183},
	year = {2001},
	month = {2001 Aug},
	pages = {4468-76},
	abstract = {NADPH is an intermediate in the oxidation of organic compounds coupled to Fe(III) reduction in Geobacter species, but Fe(III) reduction with NADPH as the electron donor has not been studied in these organisms. Crude extracts of Geobacter sulfurreducens catalyzed the NADPH-dependent reduction of Fe(III)-nitrilotriacetic acid (NTA). The responsible enzyme, which was recovered in the soluble protein fraction, was purified to apparent homogeneity in a four-step procedure. Its specific activity for Fe(III) reduction was 65 micromol. min(-1). mg(-1). The soluble Fe(III) reductase was specific for NADPH and did not utilize NADH as an electron donor. Although the enzyme reduced several forms of Fe(III), Fe(III)-NTA was the preferred electron acceptor. The protein possessed methyl viologen:NADP(+) oxidoreductase activity and catalyzed the reduction of NADP(+) with reduced methyl viologen as electron donor at a rate of 385 U/mg. The enzyme consisted of two subunits with molecular masses of 87 and 78 kDa and had a native molecular mass of 320 kDa, as determined by gel filtration. The purified enzyme contained 28.9 mol of Fe, 17.4 mol of acid-labile sulfur, and 0.7 mol of flavin adenine dinucleotide per mol of protein. The genes encoding the two subunits were identified in the complete sequence of the G. sulfurreducens genome from the N-terminal amino acid sequences derived from the subunits of the purified protein. The sequences of the two subunits had about 30\% amino acid identity to the respective subunits of the formate dehydrogenase from Moorella thermoacetica, but the soluble Fe(III) reductase did not possess formate dehydrogenase activity. This soluble Fe(III) reductase differs significantly from previously characterized dissimilatory and assimilatory Fe(III) reductases in its molecular composition and cofactor content.},
	keywords = {Amino Acid Sequence, Bacterial Proteins, Deltaproteobacteria, Ferric Compounds, FMN Reductase, Molecular Sequence Data, NADH, NADPH Oxidoreductases, NADP, Nitrilotriacetic Acid, Sequence Analysis, Protein, Sequence Homology, Amino Acid, Solubility},
	issn = {0021-9193},
	doi = {10.1128/JB.183.15.4468-4476.2001},
	author = {Kaufmann, F and Lovley, D R}
}
@article {590,
	title = {Isolation, characterization and gene sequence analysis of a membrane-associated 89 kDa Fe(III) reducing cytochrome c from Geobacter sulfurreducens.},
	journal = {Biochem J},
	volume = {359},
	year = {2001},
	month = {2001 Oct 1},
	pages = {147-52},
	abstract = {Geobacter sulfurreducens is capable of anaerobic respiration with Fe(III) as a terminal electron acceptor via a membrane-bound Fe(III) reductase activity associated with a large molecular mass cytochrome c. This cytochrome was purified by detergent extraction of the membrane fraction, Q-Sepharose ion-exchange chromatography, preparative electrophoresis, and MonoQ ion-exchange chromatography. Spectrophotometric analysis of the purified cytochrome reveals a c-type haem, with no evidence of haem a, haem b or sirohaem. The cytochrome has an M(r) of 89000 as determined by denaturing PAGE, and has an isoelectric point of 5.2 as determined by analytical isoelectric focusing. Dithionite-reduced cytochrome can donate electrons to Fe(III)-nitrilotriacetic acid and synthetic ferrihydrite, thus demonstrating that the cytochrome has redox and thermodynamic properties required for reduction of Fe(III). Analysis using cyclic voltammetry confirmed that the reduced cytochrome can catalytically transfer electrons to ferrihydrite, further demonstrating its ability to be an electron transport mediator in anaerobic Fe(III) respiration. Sequence analysis of a cloned chromosomal DNA fragment revealed a 2307 bp open reading frame (ferA) encoding a 768 amino acid protein corresponding to the 89 kDa cytochrome. The deduced amino acid sequence (FerA) translated from the open reading frame contained 12 putative haem-binding motifs, as well as a hydrophobic N-terminal membrane anchor sequence, a lipid-attachment site and an ATP/GTP-binding site. FerA displayed 20\% or less identity with amino acid sequences of other known cytochromes, although it does share some features with characterized polyhaem cytochromes c.},
	keywords = {Amino Acid Sequence, Bacterial Proteins, Chromatography, Ion Exchange, Cloning, Molecular, Cytochrome c Group, Deltaproteobacteria, DNA Primers, Electron Transport, Electrophoresis, Polyacrylamide Gel, Ferric Compounds, Gene Expression Regulation, Bacterial, Molecular Sequence Data, Molecular Weight, Nitrilotriacetic Acid, Oxidation-Reduction, Polymerase Chain Reaction, Sequence Homology, Amino Acid},
	issn = {0264-6021},
	author = {Magnuson, T S and Isoyama, N and Hodges-Myerson, A L and Davidson, G and Maroney, M J and Geesey, G G and Lovley, D R}
}
@article {643,
	title = {Stimulated anoxic biodegradation of aromatic hydrocarbons using Fe(III) ligands.},
	journal = {Nature},
	volume = {370},
	year = {1994},
	month = {1994 Jul 14},
	pages = {128-31},
	abstract = {Contamination of ground waters with water-soluble aromatic hydrocarbons, common components of petroleum pollution, often produces anoxic conditions under which microbial degradation of the aromatics is slow. Oxygen is often added to contaminated ground water to stimulate biodegradation, but this can be technically difficult and expensive. Insoluble Fe(III) oxides, which are generally abundant in shallow aquifers, are alternative potential oxidants, but are difficult for microorganisms to access. Here we report that adding organic ligands that bind to Fe(III) dramatically increases its bioavailability, and that in the presence of these ligands, rates of degradation of aromatic hydrocarbons in anoxic aquifer sediments are comparable to those in oxic sediments. We find that even benzene, which is notoriously refractory in the absence of oxygen, can be rapidly degraded. Our results suggest that increasing the bioavailability of Fe(III) by adding suitable ligands provides a potential alternative to oxygen addition for the bioremediation of petroleum-contaminated aquifers.},
	keywords = {Benzene, Biodegradation, Environmental, Ferric Compounds, Hydrocarbons, Ligands, Methane, Nitrilotriacetic Acid, Oxidation-Reduction, Toluene, Water Pollutants, Chemical},
	issn = {0028-0836},
	doi = {10.1038/370128a0},
	author = {Lovley, D R and Woodward, J C and Chapelle, F H}
}
