Structures and spectroscopic characteristics of iron(III) diethylenetriaminepentaacetic acid complexes. A non-heme iron(III) complex with relevance to the iron environment in lipoxygenases

Finnen, D. C.; Pinkerton, A. Alan; Dunham, William; Sands, Richard H.; Funk, Max O.

doi:10.1021/ic00020a034

Cited by 46 publications

(29 citation statements)

References 3 publications

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“…However, it should be stressed that at neutral pH the EPR signals of both neelaredoxin centers are quite similar to that of desulfoferrodoxin center I [14]. Furthermore, they are also similar to those of desulforedoxin [12] and diethylenetriaminepentaacetic acid iron complex [34]. Since, for both desulforedoxin and desulfoferrodoxin center I, Mossbauer studies strongly suggest a tetra-coordination, while for the iron complex an octahedral symmetry was determined by X-ray crystalography, it is clear that EPR evidence alone does not allow one to establish the structure of these iron centers.…”

Section: Discussionmentioning

confidence: 98%

A Blue Non‐Heme Iron Protein from Desulfovibrio gigas

Chen

Sharma

Gall

et al. 1994

European Journal of Biochemistry

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A novel iron-containing blue protein, named neelaredoxin, was isolated from the sulfate-reducing bacterium Desulfovibrio gigas. It is a monomeric protein with a molecular mass of 15 kDa containing two iron atoms/molecule. The N-terminal sequence of neelaredoxin has similarity to the second domain of desulfofen-odoxin, a protein purified from Desulfovibrio vulgaris Hildenborough. This finding supports the hypothesis that the gene coding for desulfoferrodoxin (rbo) might have arisen from a gene fusion [Brumlik, M. J., Leroy, G., Bruschi, M. & Voordouw, G. (1990) J. Bacteriol. 172, 7289-72921. The visible spectrum exhibits a single band at 666 nm, responsible for the blue color of the protein, which is completely bleached upon reduction with sodium ascorbate. In the oxidized state the EPR spectrum is complex, exhibiting well-resolved features at g = 7.6, 7.0, 5.9, and 5.8 which are assigned to two high-spin (5' = 5/2) mononuclear-iron (111) centers with different rhombic distortions (EID = 0.05 and = 0.08). The two iron atoms contribute identically to the visible spectrum as judged from visible redox titrations, from which a reduction potential of +190 mV was determined for both iron sites at pH 7.5. At high pH the visible and the EPR spectra become pH-dependent with a pK, above 9 : the 666-nm band shifts to 590 nm and the EPR signals are converted into a signal with g, , , = 4.7. Neelaredoxin is readily reduced both by H2/hydrogenase/ cytochrome c3 and by NADWNADH -rubredoxin oxidoreductase.Sulfate-reducing bacteria are rich in electron-carrier proteins. These proteins can be classified into three groups : flavoproteins, hemoproteins, and non-heme iron proteins. Detailed discussions concerning these proteins can be found in recent reviews [I, 21. Within the group of non-heme-iron proteins, besides the iron-sulfur-containing ferredoxins, several redox proteins with no labile sulfur have been discovered containing mononuclear or dinuclear iron centers. These include rubredoxin, desulforedoxin, desulfoferrodoxin, rubrerythrin and nigerythrin.Rubredoxin is the smallest protein (Mr = 6000) found in sulfate-reducing bacteria including Desulfovibrio gigas [3], D. vulgaris Hildenborough [4], D. desulfuricans [5] and D.salexigens [6]. The structure of the protein has been well studied [7]. This protein contains one iron atodmolecule which links to four cysteinyl residues in the polypeptide chain. Its high reduction potential (-50 to 0 mV) made it difficult to find an appropriate place in any electron transfer chain. Recently, D. gigas rubredoxin was shown to function in an aerobic electron transfer chain which allows ATP formation from polyglucose [S, 91. Desulforedoxin is another [Fel-only-

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Section: Discussionmentioning

confidence: 98%

A Blue Non‐Heme Iron Protein from Desulfovibrio gigas

Chen

Sharma

Gall

et al. 1994

European Journal of Biochemistry

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“…Unlike EDTA, the larger DTPA molecule is able to completely surround the complexed iron, thereby preventing reductants from gaining direct access to the iron. 23 The iron(III)EDTA complex is associated with a labile water molecule on the 7th coordination site. 24 This site therefore offers access to iron by reductants and hydrogen peroxide.…”

Section: Comparison Of Hydroxyl Radical Production Between Clinicallymentioning

confidence: 99%

The Fenton Activity of Iron(III) in the Presence of Deferiprone

Devanur

Neubert

Hider

2008

Journal of Pharmaceutical Sciences

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“…Observations of EPR signals at both g6 and g4.3 were frequently observed. The proportion of the signals obtained depended on the source of the sample, the stoichiometry of the redox reaction, and the pH of the solution [5,28–34]. For example, soybean lipoxygenase-1 treated with a single equivalent of 13-HPOD produced predominately g6 EPR signals, but a large amplitude g4.3 signal when treated with a molar excess of the peroxide [18].…”

Section: Discussionmentioning

confidence: 99%

“…This behavior was illustrated in Figure 5. Soybean lipoxygenase-3 treated with one equivalent of 13-HPOD at pH 6.5 produced a heterogeneous g6 EPR signal, but only a g4.3 signal when the same reaction was carried out at pH 9.5 [28]. The heterogeneity of the g6 signal of soybean lipoxygenase-1 was sensitive to the composition of the sample.…”

Section: Discussionmentioning

confidence: 99%

EPR spectroscopy and electrospray ionization mass spectrometry reveal distinctive features of the iron site in leukocyte 12-lipoxygenase

Rapp

Sharp

et al. 2009

Archives of Biochemistry and Biophysics

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The procedure for the expression and purification of recombinant porcine leukocyte 12-lipoxygenase using E. coli [K.M. Richards, L.J. Marnett, Biochemistry 36 (1997) 6692-6699] was updated to make it possible to produce enough protein for physical measurements. Electrospray ionization tandem mass spectrometry confirmed the amino acid sequence. The redox properties of the cofactor iron site were examined by EPR spectroscopy at 25 K following treatment with a variety of fatty acid hydroperoxides. Combination of the enzyme in a stoichiometric ratio with the hydroperoxides led to a g4.3 signal in EPR spectra instead of the g6 signal characteristic of similarly treated soybean lipoxygenase-1. Native 12-lipoxygenase was also subjected to electrospray ionization mass spectrometry. There was evidence for loss of the mass of an iron atom from the protein as the pH was lowered from 5 to 4. Native ions in these samples indicated that iron was lost without the protein completely unfolding.

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Structures and spectroscopic characteristics of iron(III) diethylenetriaminepentaacetic acid complexes. A non-heme iron(III) complex with relevance to the iron environment in lipoxygenases

Abstract: Synthesis and Spectroscopic and Magnetic Properties of a Unique Diamagnetic Binuclear µ-Vanadium(IV) Complex. Crystal Structure of [(tpa)V0^-0)V0(tpa)](CI04)2 (tpa = Tris(2-pyridylmethyl)amine)

Cited by 46 publications

References 3 publications

A Blue Non‐Heme Iron Protein from Desulfovibrio gigas

A Blue Non‐Heme Iron Protein from Desulfovibrio gigas

The Fenton Activity of Iron(III) in the Presence of Deferiprone

EPR spectroscopy and electrospray ionization mass spectrometry reveal distinctive features of the iron site in leukocyte 12-lipoxygenase

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