The electronic structure of the H-cluster in the [FeFe]-hydrogenase from Desulfovibrio desulfuricans: A Q-band 57Fe-ENDOR and HYSCORE study

Alexey Silakov, Eduard J. Reijerse, Simon P.J. Albracht, E. Claude Hatchikian, Wolfgang Lubitz

Research output: Contribution to journalArticle

119 Citations (Scopus)

Abstract

The active site of the 57Fe-enriched [FeFe]-hydrogenase (i.e., the "H-cluster") from Desulfovibrio desulfuricans has been examined using advanced pulse EPR methods at X- and Q-band frequencies. For both the active oxidized state (Hox) and the CO inhibited form (H ox-CO) all six 57Fe hyperfine couplings were detected. The analysis shows that the apparent spin density extends over the whole H-cluster. The investigations revealed different hyperfine couplings of all six 57Fe nuclei in the H-cluster of the Hox-CO state. Four large 57Fe hyperfine couplings in the range 20-40 MHz were found (using pulse ENDOR and TRIPLE methods) and were assigned to the [4Fe-4S] H (cubane) subcluster. Two weak 57Fe hyperfine couplings below 5 MHz were identified using Q-band HYSCORE spectroscopy and were assigned to the [2Fe]H subcluster. For the Hox state only two different 57Fe hyperfine couplings in the range 10-13 MHz were detected using pulse ENDOR. An 57Fe line broadening analysis of the X-band CW EPR spectrum indicated, however, that all six 57Fe nuclei in the H-cluster are contributing to the hyperfine pattern. It is concluded that in both states the binuclear subcluster [2Fe]H assumes a [Fe IFeII] redox configuration where the paramagnetic Fe I atom is attached to the [4Fe-4S]H subcluster. The 57Fe hyperfine interactions of the formally diamagnetic [4Fe-4S] H are due to an exchange interaction between the two subclusters as has been discussed earlier by Popescu and Münck [Popescu, C.V.; Münck, E., J. Am. Chem. Soc. 1999, 121, 7877-7884]. This exchange coupling is strongly enhanced by binding of the extrinsic CO ligand. Binding of the dihydrogen substrate may induce a similar effect, and it is therefore proposed that the observed modulation of the electronic structure by the changing ligand surrounding plays an important role in the catalytic mechanism of [FeFe]-hydrogenase.

Original languageEnglish (US)
Pages (from-to)11447-11458
Number of pages12
JournalJournal of the American Chemical Society
Volume129
Issue number37
DOIs
StatePublished - Sep 19 2007

Fingerprint

Desulfovibrio desulfuricans
Hydrogenase
Electron Spin Resonance Spectroscopy
Carbon Monoxide
Electronic structure
Paramagnetic resonance
Ligands
Exchange coupling
Exchange interactions
Frequency bands
Modulation
Spectroscopy
Atoms
Substrates
Oxidation-Reduction
Catalytic Domain
Spectrum Analysis

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Silakov, Alexey ; Reijerse, Eduard J. ; Albracht, Simon P.J. ; Hatchikian, E. Claude ; Lubitz, Wolfgang. / The electronic structure of the H-cluster in the [FeFe]-hydrogenase from Desulfovibrio desulfuricans : A Q-band 57Fe-ENDOR and HYSCORE study. In: Journal of the American Chemical Society. 2007 ; Vol. 129, No. 37. pp. 11447-11458.
@article{71bd7b4d26b44157be9f92e18815a43b,
title = "The electronic structure of the H-cluster in the [FeFe]-hydrogenase from Desulfovibrio desulfuricans: A Q-band 57Fe-ENDOR and HYSCORE study",
abstract = "The active site of the 57Fe-enriched [FeFe]-hydrogenase (i.e., the {"}H-cluster{"}) from Desulfovibrio desulfuricans has been examined using advanced pulse EPR methods at X- and Q-band frequencies. For both the active oxidized state (Hox) and the CO inhibited form (H ox-CO) all six 57Fe hyperfine couplings were detected. The analysis shows that the apparent spin density extends over the whole H-cluster. The investigations revealed different hyperfine couplings of all six 57Fe nuclei in the H-cluster of the Hox-CO state. Four large 57Fe hyperfine couplings in the range 20-40 MHz were found (using pulse ENDOR and TRIPLE methods) and were assigned to the [4Fe-4S] H (cubane) subcluster. Two weak 57Fe hyperfine couplings below 5 MHz were identified using Q-band HYSCORE spectroscopy and were assigned to the [2Fe]H subcluster. For the Hox state only two different 57Fe hyperfine couplings in the range 10-13 MHz were detected using pulse ENDOR. An 57Fe line broadening analysis of the X-band CW EPR spectrum indicated, however, that all six 57Fe nuclei in the H-cluster are contributing to the hyperfine pattern. It is concluded that in both states the binuclear subcluster [2Fe]H assumes a [Fe IFeII] redox configuration where the paramagnetic Fe I atom is attached to the [4Fe-4S]H subcluster. The 57Fe hyperfine interactions of the formally diamagnetic [4Fe-4S] H are due to an exchange interaction between the two subclusters as has been discussed earlier by Popescu and M{\"u}nck [Popescu, C.V.; M{\"u}nck, E., J. Am. Chem. Soc. 1999, 121, 7877-7884]. This exchange coupling is strongly enhanced by binding of the extrinsic CO ligand. Binding of the dihydrogen substrate may induce a similar effect, and it is therefore proposed that the observed modulation of the electronic structure by the changing ligand surrounding plays an important role in the catalytic mechanism of [FeFe]-hydrogenase.",
author = "Alexey Silakov and Reijerse, {Eduard J.} and Albracht, {Simon P.J.} and Hatchikian, {E. Claude} and Wolfgang Lubitz",
year = "2007",
month = "9",
day = "19",
doi = "10.1021/ja072592s",
language = "English (US)",
volume = "129",
pages = "11447--11458",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "37",

}

The electronic structure of the H-cluster in the [FeFe]-hydrogenase from Desulfovibrio desulfuricans : A Q-band 57Fe-ENDOR and HYSCORE study. / Silakov, Alexey; Reijerse, Eduard J.; Albracht, Simon P.J.; Hatchikian, E. Claude; Lubitz, Wolfgang.

In: Journal of the American Chemical Society, Vol. 129, No. 37, 19.09.2007, p. 11447-11458.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The electronic structure of the H-cluster in the [FeFe]-hydrogenase from Desulfovibrio desulfuricans

T2 - A Q-band 57Fe-ENDOR and HYSCORE study

AU - Silakov, Alexey

AU - Reijerse, Eduard J.

AU - Albracht, Simon P.J.

AU - Hatchikian, E. Claude

AU - Lubitz, Wolfgang

PY - 2007/9/19

Y1 - 2007/9/19

N2 - The active site of the 57Fe-enriched [FeFe]-hydrogenase (i.e., the "H-cluster") from Desulfovibrio desulfuricans has been examined using advanced pulse EPR methods at X- and Q-band frequencies. For both the active oxidized state (Hox) and the CO inhibited form (H ox-CO) all six 57Fe hyperfine couplings were detected. The analysis shows that the apparent spin density extends over the whole H-cluster. The investigations revealed different hyperfine couplings of all six 57Fe nuclei in the H-cluster of the Hox-CO state. Four large 57Fe hyperfine couplings in the range 20-40 MHz were found (using pulse ENDOR and TRIPLE methods) and were assigned to the [4Fe-4S] H (cubane) subcluster. Two weak 57Fe hyperfine couplings below 5 MHz were identified using Q-band HYSCORE spectroscopy and were assigned to the [2Fe]H subcluster. For the Hox state only two different 57Fe hyperfine couplings in the range 10-13 MHz were detected using pulse ENDOR. An 57Fe line broadening analysis of the X-band CW EPR spectrum indicated, however, that all six 57Fe nuclei in the H-cluster are contributing to the hyperfine pattern. It is concluded that in both states the binuclear subcluster [2Fe]H assumes a [Fe IFeII] redox configuration where the paramagnetic Fe I atom is attached to the [4Fe-4S]H subcluster. The 57Fe hyperfine interactions of the formally diamagnetic [4Fe-4S] H are due to an exchange interaction between the two subclusters as has been discussed earlier by Popescu and Münck [Popescu, C.V.; Münck, E., J. Am. Chem. Soc. 1999, 121, 7877-7884]. This exchange coupling is strongly enhanced by binding of the extrinsic CO ligand. Binding of the dihydrogen substrate may induce a similar effect, and it is therefore proposed that the observed modulation of the electronic structure by the changing ligand surrounding plays an important role in the catalytic mechanism of [FeFe]-hydrogenase.

AB - The active site of the 57Fe-enriched [FeFe]-hydrogenase (i.e., the "H-cluster") from Desulfovibrio desulfuricans has been examined using advanced pulse EPR methods at X- and Q-band frequencies. For both the active oxidized state (Hox) and the CO inhibited form (H ox-CO) all six 57Fe hyperfine couplings were detected. The analysis shows that the apparent spin density extends over the whole H-cluster. The investigations revealed different hyperfine couplings of all six 57Fe nuclei in the H-cluster of the Hox-CO state. Four large 57Fe hyperfine couplings in the range 20-40 MHz were found (using pulse ENDOR and TRIPLE methods) and were assigned to the [4Fe-4S] H (cubane) subcluster. Two weak 57Fe hyperfine couplings below 5 MHz were identified using Q-band HYSCORE spectroscopy and were assigned to the [2Fe]H subcluster. For the Hox state only two different 57Fe hyperfine couplings in the range 10-13 MHz were detected using pulse ENDOR. An 57Fe line broadening analysis of the X-band CW EPR spectrum indicated, however, that all six 57Fe nuclei in the H-cluster are contributing to the hyperfine pattern. It is concluded that in both states the binuclear subcluster [2Fe]H assumes a [Fe IFeII] redox configuration where the paramagnetic Fe I atom is attached to the [4Fe-4S]H subcluster. The 57Fe hyperfine interactions of the formally diamagnetic [4Fe-4S] H are due to an exchange interaction between the two subclusters as has been discussed earlier by Popescu and Münck [Popescu, C.V.; Münck, E., J. Am. Chem. Soc. 1999, 121, 7877-7884]. This exchange coupling is strongly enhanced by binding of the extrinsic CO ligand. Binding of the dihydrogen substrate may induce a similar effect, and it is therefore proposed that the observed modulation of the electronic structure by the changing ligand surrounding plays an important role in the catalytic mechanism of [FeFe]-hydrogenase.

UR - http://www.scopus.com/inward/record.url?scp=35048857033&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=35048857033&partnerID=8YFLogxK

U2 - 10.1021/ja072592s

DO - 10.1021/ja072592s

M3 - Article

C2 - 17722921

AN - SCOPUS:35048857033

VL - 129

SP - 11447

EP - 11458

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 37

ER -