Magnetic studies of the four-iron high-potential, non-heme protein from Chromatium vinosum

Antanaitis, B C; Moss, Thomas H.

doi:10.1016/0005-2795(75)90093-8

Cited by 87 publications

(49 citation statements)

References 31 publications

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“…Both the overall spectral shape as well as the actual g-values of these species are remarkably similar to those observed for soluble HIPIPs (Table 1). The observed heterogeneity is reminiscent of that described for the HIPIPs isolated from Chromatium vinosum [9,10], Ectothiorhodospira vacuolata [16] and Rhodocyclus gelatinosa [17]. Its origin in Rhodothermus is not yet known.…”

Section: Resultsmentioning

confidence: 60%

“…Whether this representation of the experimental spectrum is correct remains a question of debate. The original EPR spectrum from Chromatium vinosum HIPIP was interpreted as resulting from three distinct species [9]. However, Dunham et al [lo] proposed an alternative interpretation of the EPR data, suggesting that the spectral heterogeneity was due both to an intrinsic, and still unexplained, protein heterogeneity (rhombic species with g,,,,, at 2.07) and to protein dimerization.…”

Section: 00mentioning

confidence: 99%

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A membrane‐bound HIPIP type center in the thermohalophile Rhodothermus marinus

et al. 1994

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A HIPIP-type center was discovered in intact membranes of the thermohalophilic aerobe Rhodothermus marinus. In both the membranebound state and after detergent solubilization and partial purification, this center exhibits an almost axial EPR spectrum, with g-values at 2.13 and 2.03, similar to those of soluble HIPIP proteins isolated from purple bacteria. It has a high reduction potential, of 260 mV at pH 7.5. Rhodothermus HIPIP is involved in the main membrane-bound electron-transfer pathway, being reduced by NADH or succinate only in the presence of cyanide. The possible physiological function of this novel HIPIP-type center is discussed.

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Section: Resultsmentioning

confidence: 60%

Section: 00mentioning

confidence: 99%

A membrane‐bound HIPIP type center in the thermohalophile Rhodothermus marinus

et al. 1994

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“…The shape of the EPR signal resembles that of a HiPIP-type [4Fe-4S] 3+ cluster. The temperature behavior of the signal, however, is not typical for such a cluster [29,30]. Below 20 K it is not possible to measure the signal without saturation.…”

Section: Resultsmentioning

confidence: 97%

Possible direct involvement of the active‐site [4Fe–4S] cluster of the GcpE enzyme from Thermus thermophilus in the conversion of MEcPP

Adedeji¹,

Hernandez²,

Wiesner³

et al. 2006

FEBS Letters

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The GcpE enzyme converts 2-C-methyl-D D-erythritol-2,4-cyclodiphosphate (MEcPP) into (E)-4-hydroxy-3-methylbut-2-enyl diphosphate (HMBPP) in the penultimate step of the DOXP pathway for isoprene biosynthesis. Purification of the enzyme under exclusion of air leads to a preparation that contains solely [4Fe-4S] clusters. Kinetic studies showed that in the presence of the artificial reductant dithionite and MEcPP a new transient iron-sulfur-based signal is detected in electron paramagnetic resonance (EPR) spectroscopy. Similarity of this EPR signal to that detected in ferredoxin:thioredoxin reductase indicates that during the reaction an intermediate is directly bound to the active-site cluster.

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“…The 2(Fe,S,) ferredoxin from Clostridium pasteurianum is a low molecular weight iron sulfur protein [l-3]; in the oxidized state each cluster formally contains two iron (III) and two iron (II) ions [4]. Owing to antiferromagnetic exchange coupling the ground state is S=O [4,5].…”

Section: Introdijctionmentioning

confidence: 99%

“…Owing to antiferromagnetic exchange coupling the ground state is S=O [4,5]. At room temperature some paramagnetism arises from occupancy of the excited states; the overall magnetic moment at 298 K is =4.1 BM per cluster 161. magnetic compounds have been reported, in particular for systems containing low spin iron (III), for which the nuclear relaxation rates are only slightly increased with respect to diamagnetic systems [13-171.…”

Section: Introdijctionmentioning

confidence: 99%

2D ¹H NMR studies of oxidized 2(Fe₄S₄) ferredoxin from Clostridium pasteurianum

et al. 1991

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Oxidized ferredoxin from Clostridium pasteurianum, containing two Fe& clusters, has been investigated using 2D 'H NMR spectroscopy at 600MHz. 2D NMR experiments allowed complete assignment of the sixteen isotropically shifted signals corresponding to thefl-CH, protons of the eight metal coordinated cysteines. Geminal connectivities of Cys jl-CH2 protons were identified through magnitude COSY experiments and confirmed through 2D NOESY experiments. A few additional signals could be assigned to the corresponding a-CH protons. The importance of 2D experiments to achieve firm assignments of isotropically shifted signals in pammagnetic metalloproteins is stressed.Ferredoxin; Iron-sulfur cluster; 2D NMR; Metalloprotein INTRODIJCTIONThe 2(Fe,S,) ferredoxin from Clostridium pasteurianum is a low molecular weight iron sulfur protein [l-3]; in the oxidized state each cluster formally contains two iron (III) and two iron (II) ions [4]. Owing to antiferromagnetic exchange coupling the ground state is S=O [4,5]. At room temperature some paramagnetism arises from occupancy of the excited states; the overall magnetic moment at 298 K is =4.1 BM per cluster 161. magnetic compounds have been reported, in particular for systems containing low spin iron (III), for which the nuclear relaxation rates are only slightly increased with respect to diamagnetic systems [13-171.2D 'H NMR experiments have been developed and extensively utilized for the determination of the solution structure of diamagnetic compounds [7,8]. In these systems the 2D pulse sequences take place in a time negligible with respect to proton relaxation times; magnetization transfer occurs in a time shorter or of the same order of magnitude. On the other hand, paramagnetic systems are characterized by drastic enhancements of nuclear relaxation rates [9,10]; so it often happens that the spin system reaches equilibrium without transferring detectable amounts of magnetization from one spin set to another. This fact has heavily hindered the application of 2D NMR techniqtit; ;o paramagnetic systems [I 1,121. In this frame, we here report a 2D NOESY and COSY study of the oxidized 2(Fe&) ferredoxin from Ciostridium pasteurianum. We demonstrate that, by an accurate choice of the experimental parameters, 2D NMR experiments can be fruitfully applied to the investigation of paramagnetic iron-sulfur clusters and can provide valuable information for firm assignments of the isotropically shifted lines. MATERIALS AND METHODSCfosrridium pasfeuriurwm was grown and ferredoxin isolated and purified according to the method of Rabinowitz [l&19]. The purity of the sample was checked by absorption spectroscopy by monitoring the AJA,, absorbance ratio. For 'H NMR experiments the protein was dissolved in 50 mM NaPi buffer, pH 8.0. Deuteration of the sample was achieved by utilizing an ultrafiltration Amicon cell, equipped with a YMl membrane. At least five changes of deuterated buffer were performed to ensure satisfactory solvent exchange. The pH values are reported as uncorrected pH meter ...

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Magnetic studies of the four-iron high-potential, non-heme protein from Chromatium vinosum

Cited by 87 publications

References 31 publications

A membrane‐bound HIPIP type center in the thermohalophile Rhodothermus marinus

A membrane‐bound HIPIP type center in the thermohalophile Rhodothermus marinus

Possible direct involvement of the active‐site [4Fe–4S] cluster of the GcpE enzyme from Thermus thermophilus in the conversion of MEcPP

2D ¹H NMR studies of oxidized 2(Fe₄S₄) ferredoxin from Clostridium pasteurianum

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Magnetic studies of the four-iron high-potential, non-heme protein from Chromatium vinosum

Cited by 87 publications

References 31 publications

A membrane‐bound HIPIP type center in the thermohalophile Rhodothermus marinus

A membrane‐bound HIPIP type center in the thermohalophile Rhodothermus marinus

Possible direct involvement of the active‐site [4Fe–4S] cluster of the GcpE enzyme from Thermus thermophilus in the conversion of MEcPP

2D 1H NMR studies of oxidized 2(Fe4S4) ferredoxin from Clostridium pasteurianum

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2D ¹H NMR studies of oxidized 2(Fe₄S₄) ferredoxin from Clostridium pasteurianum