@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 {611,
	title = {Lack of production of electron-shuttling compounds or solubilization of Fe(III) during reduction of insoluble Fe(III) oxide by Geobacter metallireducens.},
	journal = {Appl Environ Microbiol},
	volume = {66},
	year = {2000},
	month = {2000 May},
	pages = {2248-51},
	abstract = {Studies with the dissimilatory Fe(III)-reducing microorganism Geobacter metallireducens demonstrated that the common technique of separating Fe(III)-reducing microorganisms and Fe(III) oxides with semipermeable membranes in order to determine whether the Fe(III) reducers release electron-shuttling compounds and/or Fe(III) chelators is invalid. This raised doubts about the mechanisms for Fe(III) oxide reduction by this organism. However, several experimental approaches indicated that G. metallireducens does not release electron-shuttling compounds and does not significantly solubilize Fe(III) during Fe(III) oxide reduction. These results suggest that G. metallireducens directly reduces insoluble Fe(III) oxide.},
	keywords = {Deltaproteobacteria, Electron Transport, Ferric Compounds, Iron, Kinetics, Oxidation-Reduction, Solubility},
	issn = {0099-2240},
	author = {Nevin, K P and Lovley, D R}
}
