Probing magnetic properties of the reduced [2Fe-2S] cluster of the ferredoxin from Arthrospira platensis by 1H ENDOR spectroscopy

Canne, Christoph; Ebelshäuser, Michael; Shergill, Jasvinder K.; Cammack, Richard; Kappl, Reinhard; Hüttermann, Jürgen

doi:10.1007/pl00021451

Cited by 17 publications

(39 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition several NH-or OH-groups of neighboring amino acids are within hydrogen bonding distance to the sulfurs of the coordinated cysteine tigands to Fel, which may raise its microscopic redox potential [3,23,24]. Our orientation-selective ENDOR study has confirmed this assignment [14].…”

Section: Introductionsupporting

confidence: 74%

“…1. We have presented earlier the first analysis of the orientation-selective proton ENDOR spectra of a protein containing a [2Fe-2S] center in Arthrospira (formerly Spirulina)platensis [14]. A. platensis ferredoxin belongs to the former class and is representative of a wide range of clusters in electron-transfer proteins in plants, vertebrates and bacteria [1].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Probing electronic and structural properties of the reduced [2Fe−2S] cluster by orientation-selective1H ENDOR spectroscopy: Adrenodoxin versus rieske iron-sulfur protein

et al. 2006

Self Cite

View full text Add to dashboard Cite

The IH electron-nuclear double resonance (ENDOR) spectra in frozen buffer solutions of the reduced [2Fe-2S] clusters in adrenodoxin (Adx) and in the "Rieske" iron-sulfur protein (ISP) from the bovine mitochondrial bcl complex were measured at low temperatures (5-20 K) and analyzed by spectra reconstruction. A single paramagnetic species with iron valence states (II) and (III) connected uniquely to the cluster irons was found in both proteins. For Adx, the experimental spectra from 23 ¡ positions across the nearly axial (gm~x = 2.0241, gint -----1.9347, and gro,, = 1.9331) electron paramagnetic resonance (EPR) spectrum were analyzed. Four larger hyperfine couplings were assigned to the cysteine [3-protons near the Fe(III) ion. Transfer into the crystal structure showed that the Fe(III) ion was coordinated to the residues Cys55 and Cys92. The spin density was estimated as + 1.60 for the Fe(III) and -0.6 for the Fe(II) ion, respectively. The g-tensor direction with respect to the cluster showed strong similarities with the earlier assignment in Arthospira platensis ferredoxin (Canne C., Ebelshauser M., Gay E., Shergill J.K., Cammack R., Kappl R., Hª J.: J. Biol. Inorg. Chem. 5, 514, 2000). Ah Adx mutant (T54A) exhibiting a change (70 mV) in redox potential showed no significant influence at the [2Fe-2S] cluster. The Rieske ISP was subjected to the same analysis. The ENDOR spectra from 35 field positions across the rhombic (gmax = 2.028, gint = 1.891, and gm~, = 1.757) EPR spectrum were simulated. Three major proton contributions were identified from the o¡ behavior. Two were assigned to cysteine ~-protons and one to a ~-proton of Hisl41. In contrast to Adx, the direction of the gm,~-component was found to lie roughly in the FeScore plane and the largest proton coupling occurred along g~,t. The spin population was estimated as about +1.6 for the oxidized and -0.55 for the reduced iron.

show abstract

Section: Introductionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Probing electronic and structural properties of the reduced [2Fe−2S] cluster by orientation-selective1H ENDOR spectroscopy: Adrenodoxin versus rieske iron-sulfur protein

et al. 2006

Self Cite

View full text Add to dashboard Cite

show abstract

“…Using this specific direction for the single site occurring in that HiPIP, a non-cysteine-bound, dipolar proton of the residue phenylalanine 44 carne into play which gave a prominent, discemable interaction in the ENDOR spectra. This was different from typical findings in [Fe2S2] clusters in which mainly the cysteine-bound [3-pro-tons were responsible for the major couplings [8,9]. One of the goals of the present study on E. halophila HiPIP I was therefore to test by site-directed mutagenesis the role of the respective residue in this HiPIE The other airo conceros the site isomerism discussed above.…”

Section: Introductionmentioning

confidence: 42%

“…In [Fe2S2] clusters like in plant and vertebrate ferredoxins or in the "Rieske" cluster, the extra electron produced upon reduction of the complex resides on one specific iron. This has been convincingly proven by M6ssbauer, paramagnetic NMR and electron-nuclear double resonance (ENDOR) spectroscopy [6][7][8]. It appears that in the all-cysteine coordinated [FezS_, ] ferredoxins the site specificity is governed by the degree of solvent exposure and the number of polarizable protons (e.g., NH) in the polypeptide backbone vicinity [6,8,9].…”

Section: Introductionmentioning

confidence: 78%

“…This has been convincingly proven by M6ssbauer, paramagnetic NMR and electron-nuclear double resonance (ENDOR) spectroscopy [6][7][8]. It appears that in the all-cysteine coordinated [FezS_, ] ferredoxins the site specificity is governed by the degree of solvent exposure and the number of polarizable protons (e.g., NH) in the polypeptide backbone vicinity [6,8,9]. For the Rieske cluster in which two histidines replace the cysteines in the coordination of one of the irons, it is this site which is reduced [9,10].…”

Section: Introductionmentioning

confidence: 96%

See 1 more Smart Citation

Site-specific oxidation of the [Fe4S4] cubanes in high-potential iron sulfur proteins as probed by EPR and orientation-selective proton ENDOR spectroscopy:Ectothiorhodospira halophila I versusRhodocyclus tenuis

et al. 2007

Self Cite

View full text Add to dashboard Cite

Electron paramagnetic resonance (EPR) and proton ENDOR (electron-nuclear double resonanee) spectroscopies were used to analyze the struetural and eleetronic parameters of the oxidized [Fe4S4] cubane clusters in high-potential iron sulfur proteins (HiPIPs) from Ectothiorhodospira halophila (HiPIP I) and Rhodocyclus tenuis. The E. halophila HiPIP I EPR spectra at X-and Q-band revealed a dominant species (simulated with gm~ = 2.1425, g,n, = 2.0315, gmm = 2.0296) anda minor speeies (ea. 5-10% contribution) which was not analyzed further. For R. tenuis HiPIP the EPR spectrum contained a single species only (g~x = 2.1140, g~,, = 2.0392, gm~, = 2.0215), i.e., with gmax significantly smaller than that of the E. halophila protein. Orientation-selected proton ENDOR spectra of HiPIP I of E. halophila were reconstructed by simulation with slight modifications of the crystal structure data. ENDOR from two mutants, F36S and F36G, of E. halophila HiPIP I gave evidente fora common assignment of a HB2 proton of a phenylalanine residue (36 and 44, respectively, in isoenzymes I and II as reported earlier) interacting with the mixed-valence pair iron ions Fe2 and Fe3. For R. tenuis HiPIE the ENDOR spectra were assigned to arise from Fe3 and Fe4 as mixedvalence pair under the assumption of ah unchanged intrinsic g-tensor symmetry. The resulting site specificity of the cubane oxidation was discussed in relation to structural requirements and redox potentials of the two HiPIPs.

show abstract

Theory of chemical bonds in metalloenzymes III: Full geometry optimization and vibration analysis of ferredoxin‐type [2Fe–2S] cluster

Shoji

Koizumi

Taniguchi

et al. 2006

Int J of Quantum Chemistry

View full text Add to dashboard Cite

The nature of chemical bonds in a ferredoxin-type [2Fe-2S] cluster hasbeen investigated on the basis of natural orbitals and several bond indices developed in Parts I and II of this study. The broken-symmetry hybrid density functional theory (BS-HDFT) with spin projection approach has been applied to elucidate the natural orbitals and occupation numbers for a model compound [Fe 2 S 2 (SCH 3 ) 4 ] (1), which is used to calculate the indices. The molecular structure, vibration frequencies, electronic structures, and magnetic properties in both oxidized and reduced forms of 1 have been calculated and compared with the experimental values. The optimized molecular structures after approximate spin projection have been in good agreement with experimental data. The structure changes upon one-electron reduction have been slight (Ͻ0.1 Å) and only limited around one side of the Fe atom. Raman and infrared (IR) spectra have been calculated, and their vibration modes have been assigned using the bridging 34 S isotope substitution. Their magnetic properties have been examined in terms of spin Hamiltonians that contain exchange interactions and double exchange interactions. The BS-HDFT methods have provided the magnetic parameters; i.e., effective exchange integral ( J) values and valence delocalization (B) values, which agree with the experimental results. It is found that large charge transfer (CT) from the bridging sulfur to the iron atoms has led to the strong antiferromagnetic interactions between iron atoms.

show abstract

Probing magnetic properties of the reduced [2Fe-2S] cluster of the ferredoxin from Arthrospira platensis by 1H ENDOR spectroscopy

Cited by 17 publications

References 0 publications

Probing electronic and structural properties of the reduced [2Fe−2S] cluster by orientation-selective1H ENDOR spectroscopy: Adrenodoxin versus rieske iron-sulfur protein

Probing electronic and structural properties of the reduced [2Fe−2S] cluster by orientation-selective1H ENDOR spectroscopy: Adrenodoxin versus rieske iron-sulfur protein

Site-specific oxidation of the [Fe4S4] cubanes in high-potential iron sulfur proteins as probed by EPR and orientation-selective proton ENDOR spectroscopy:Ectothiorhodospira halophila I versusRhodocyclus tenuis

Theory of chemical bonds in metalloenzymes III: Full geometry optimization and vibration analysis of ferredoxin‐type [2Fe–2S] cluster

Contact Info

Product

Resources

About