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Hydride binding to the active site of [FeFe]-hydrogenase

Chernev, Petko ; Lambertz, Camilla ; Brünje, Annika ; Leidel, Nils ; Sigfridsson, Kajsa G.V. LU ; Kositzki, Ramona ; Hsieh, Chung Hung ; Yao, Shenglai ; Schiwon, Rafael and Driess, Matthias , et al. (2014) In Inorganic Chemistry 53(22). p.12164-12177
Abstract

[FeFe]-hydrogenase from green algae (HydA1) is the most efficient hydrogen (H2) producing enzyme in nature and of prime interest for (bio)technology. Its active site is a unique six-iron center (H-cluster) composed of a cubane cluster, [4Fe4S]H, cysteine-linked to a diiron unit, [2Fe]H, which carries unusual carbon monoxide (CO) and cyanide ligands and a bridging azadithiolate group. We have probed the molecular and electronic configurations of the H-cluster in functional oxidized, reduced, and super-reduced or CO-inhibited HydA1 protein, in particular searching for intermediates with iron-hydride bonds. Site-selective X-ray absorption and emission spectroscopy were used to distinguish between low-and... (More)

[FeFe]-hydrogenase from green algae (HydA1) is the most efficient hydrogen (H2) producing enzyme in nature and of prime interest for (bio)technology. Its active site is a unique six-iron center (H-cluster) composed of a cubane cluster, [4Fe4S]H, cysteine-linked to a diiron unit, [2Fe]H, which carries unusual carbon monoxide (CO) and cyanide ligands and a bridging azadithiolate group. We have probed the molecular and electronic configurations of the H-cluster in functional oxidized, reduced, and super-reduced or CO-inhibited HydA1 protein, in particular searching for intermediates with iron-hydride bonds. Site-selective X-ray absorption and emission spectroscopy were used to distinguish between low-and high-spin iron sites in the two subcomplexes of the H-cluster. The experimental methods and spectral simulations were calibrated using synthetic model complexes with ligand variations and bound hydride species. Distinct X-ray spectroscopic signatures of electronic excitation or decay transitions in [4Fe4S]H and [2Fe]H were obtained, which were quantitatively reproduced by density functional theory calculations, thereby leading to specific H-cluster model structures. We show that iron-hydride bonds are absent in the reduced state, whereas only in the super-reduced state, ligand rotation facilitates hydride binding presumably to the Fe-Fe bridging position at [2Fe]H. These results are in agreement with a catalytic cycle involving three main intermediates and at least two protonation and electron transfer steps prior to the H2 formation chemistry in [FeFe]-hydrogenases.

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publishing date
type
Contribution to journal
publication status
published
in
Inorganic Chemistry
volume
53
issue
22
pages
14 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:25369169
  • scopus:84911091467
ISSN
0020-1669
DOI
10.1021/ic502047q
language
English
LU publication?
no
id
9cb8bfde-61c1-44c6-9e15-85fd2072974a
date added to LUP
2020-01-15 10:13:47
date last changed
2024-05-01 04:09:49
@article{9cb8bfde-61c1-44c6-9e15-85fd2072974a,
  abstract     = {{<p>[FeFe]-hydrogenase from green algae (HydA1) is the most efficient hydrogen (H<sub>2</sub>) producing enzyme in nature and of prime interest for (bio)technology. Its active site is a unique six-iron center (H-cluster) composed of a cubane cluster, [4Fe4S]<sub>H</sub>, cysteine-linked to a diiron unit, [2Fe]<sub>H</sub>, which carries unusual carbon monoxide (CO) and cyanide ligands and a bridging azadithiolate group. We have probed the molecular and electronic configurations of the H-cluster in functional oxidized, reduced, and super-reduced or CO-inhibited HydA1 protein, in particular searching for intermediates with iron-hydride bonds. Site-selective X-ray absorption and emission spectroscopy were used to distinguish between low-and high-spin iron sites in the two subcomplexes of the H-cluster. The experimental methods and spectral simulations were calibrated using synthetic model complexes with ligand variations and bound hydride species. Distinct X-ray spectroscopic signatures of electronic excitation or decay transitions in [4Fe4S]<sub>H</sub> and [2Fe]<sub>H</sub> were obtained, which were quantitatively reproduced by density functional theory calculations, thereby leading to specific H-cluster model structures. We show that iron-hydride bonds are absent in the reduced state, whereas only in the super-reduced state, ligand rotation facilitates hydride binding presumably to the Fe-Fe bridging position at [2Fe]<sub>H</sub>. These results are in agreement with a catalytic cycle involving three main intermediates and at least two protonation and electron transfer steps prior to the H<sub>2</sub> formation chemistry in [FeFe]-hydrogenases.</p>}},
  author       = {{Chernev, Petko and Lambertz, Camilla and Brünje, Annika and Leidel, Nils and Sigfridsson, Kajsa G.V. and Kositzki, Ramona and Hsieh, Chung Hung and Yao, Shenglai and Schiwon, Rafael and Driess, Matthias and Limberg, Christian and Happe, Thomas and Haumann, Michael}},
  issn         = {{0020-1669}},
  language     = {{eng}},
  month        = {{11}},
  number       = {{22}},
  pages        = {{12164--12177}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Inorganic Chemistry}},
  title        = {{Hydride binding to the active site of [FeFe]-hydrogenase}},
  url          = {{http://dx.doi.org/10.1021/ic502047q}},
  doi          = {{10.1021/ic502047q}},
  volume       = {{53}},
  year         = {{2014}},
}