Desulfovibrio desulfuricans iron hydrogenase: the structure shows unusual coordination to an active site Fe binuclear center

Nicolet, Yvain; Piras, C.; Legrand, Pierre; Hatchikian, Claude E.; Fontecilla‐Camps, Juan C.

doi:10.1016/s0969-2126(99)80005-7

Cited by 1,350 publications

(1,252 citation statements)

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“…9,10 The active site of [FeFe]-hydrogenases, referred to as the H-cluster, is a unique six iron cluster consisting of a [4Fe4S] cluster bridged via a cysteinyl thiolate to a diiron subsite. 5,6 This diiron subcluster, although biologically unprecedented, is highly reminiscent of known organometallic complexes. As shown in Figure 1, it consists of a dithiolate ligand bridging the two iron ions as well as the strong π-acceptors CO and CNat each iron center.…”

Section: Introductionmentioning

confidence: 99%

“…Organometallic complexes of the type [(µ-SR 2 )Fe 2 (CO) 6 ] and their derivatives in which one or more of the carbonyls have been replaced with more strongly σ-donating ligands such as phosphines, have been used extensively as both structural and functional mimics of [FeFe]-hyrogenases. 3,11,12 Although the natural enzyme features iron centers in square pyramidal environments that are inverted relative to each other such that a terminal open coordination site is available, the irons in most of these model complexes are in the so-called "eclipsed" geometry in which the two pyramids have the same orientation.…”

Section: Introductionmentioning

confidence: 99%

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Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

et al. 2014

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Abstract:Two pentacoordinate mononuclear iron carbonyls of the form (bdt)Fe(CO)P 2 [bdt = benzene-1,2-dithiolate; P 2 = 1,1'-diphenylphosphinoferrocene (1) or methyl-2-{bis(diphenylphosphinomethyl)amino}acetate (2)] were prepared as functional, biomimetic models for the distal iron (Fe d ) of the active site of [FeFe]-hydrogenase. Xray crystal structures of the complexes reveal that, despite similar ν(CO) stretching band frequencies, the two complexes have different coordination geometries. In X-ray crystal structures, the iron center of 1 is in a distorted trigonal bipyramidal arrangement, and that of 2 is in a distorted square pyramidal geometry. Electrochemical investigation shows that both complexes catalyze electrochemical proton reduction from acetic acid at mild overpotential, 0.17 and 0.38 V for 1 and 2, respectively. Although coordinatively unsaturated, the complexes display only weak, reversible binding affinity towards CO(1 bar). However, ligand centered protonation by the strong acid, HBF 4 .OEt 2 , triggers quantitative CO uptake by 1 to form a dicarbonyl analogue [1(H)-CO] + that can be reversibly converted back to 1 by deprotonation using NEt 3 . Both crystallographically determined distances within the bdt ligand and DFT calculations suggest that the iron centers in both 1 and 2 are partially reduced at the expense of partial oxidation of the bdt ligand. Ligand protonation interrupts this extensive electronic delocalization between the Fe and bdt making 1(H) + susceptible to external CO binding.3

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

et al. 2014

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“…1) [5][6][7][8][9]. However, the [NiFe]-and [FeFe]-hydrogenases do not use the same molecular strategy to link the two metal ions of the dinuclear site: whereas two protein-bound cysteines provide the two sulfur bridges in [NiFe]-hydrogenases, this bridge in [FeFe]-hydrogenases is provided by a non-protein dithiolate ligand, whose composition has not been determined experimentally but was proposed, on the basis of X-ray crystallographic data, to be À SCH 2 XCH 2 S À , with X being either nitrogen, oxygen or carbon [10]. Because of the potential role of an amine group in proton trafficking, we consider the first hypothesis as the most likely [9].…”

Section: Introductionmentioning

confidence: 99%

The role of the maturase HydG in [FeFe]‐hydrogenase active site synthesis and assembly

et al. 2009

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a b s t r a c t[FeFe]-hydrogenases catalyze the protons/hydrogen interconversion through a unique di-iron active site consisting of three CO and two CN ligands, and a non-protein SCH 2 XCH 2 S (X = N or O) dithiolate bridge. Site assembly requires two ''Radical-S-adenosylmethionine (SAM or AdoMet)" iron-sulfur enzymes, HydE and HydG, and one GTPase, HydF. The sequence homology between HydG and ThiH, a Radical-SAM enzyme which cleaves tyrosine into p-cresol and dehydroglycine, and the finding of a similar cleavage reaction catalyzed by HydG suggests a mechanism for hydrogenase maturation. Here we propose that HydG is specifically involved in the synthesis of the dithiolate ligand, with two tyrosine-derived dehydroglycines as precursors along with an [FeS] cluster of HydG functioning both as electron shuttle and source of the sulfur atoms.

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“…The FeFe hydrogenase is the most active catalyst for H 2 evolution, with a fascinating turnover frequency (TOF) up to 6000À9000 s À1 . 16,17 Since the structure of FeFe hydrogenase was resolved in 1998 (as shown in Figure 4), 35,36 45,46 For its high activity and relatively low working potential, this type of complex has been recognized as a functional hydrogenase mimic. 47,48 To achieve lightdriven H 2 evolution, hydrogenase mimics were combined with light harvesters.…”

Section: Hybrid Photocatalysts For H 2 Evolutionmentioning

confidence: 99%

Hybrid Artificial Photosynthetic Systems Comprising Semiconductors as Light Harvesters and Biomimetic Complexes as Molecular Cocatalysts

2013

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S olar fuel production through artificial photosynthesis may be a key to generating abundant and clean energy, thus addressing the high energy needs of the world's expanding population. As the crucial components of photosynthesis, the artificial photosynthetic system should be composed of a light harvester (e.g., semiconductor or molecular dye), a reduction cocatalyst (e.g., hydrogenase mimic, noble metal), and an oxidation cocatalyst (e.g., photosystem II mimic for oxygen evolution from water oxidation). Solar fuel production catalyzed by an artificial photosynthetic system starts from the absorption of sunlight by the light harvester, where charge separation takes place, followed by a charge transfer to the reduction and oxidation cocatalysts, where redox reaction processes occur. One of the most challenging problems is to develop an artificial photosynthetic solar fuel production system that is both highly efficient and stable. The assembly of cocatalysts on the semiconductor (light harvester) not only can facilitate the charge separation, but also can lower the activation energy or overpotential for the reactions. An efficient light harvester loaded with suitable reduction and oxidation cocatalysts is the key for high efficiency of artificial photosynthetic systems.In this Account, we describe our strategy of hybrid photocatalysts using semiconductors as light harvesters with biomimetic complexes as molecular cocatalysts to construct efficient and stable artificial photosynthetic systems. We chose semiconductor nanoparticles as light harvesters because of their broad spectral absorption and relatively robust properties compared with a natural photosynthesis system. Using biomimetic complexes as cocatalysts can significantly facilitate charge separation via fast charge transfer from the semiconductor to the molecular cocatalysts and also catalyze the chemical reactions of solar fuel production. The hybrid photocatalysts supply us with a platform to study the photocatalytic mechanisms of H 2 /O 2 evolution and CO 2 reduction at the molecular level and to bridge natural and artificial photosynthesis. We demonstrate the feasibility of the hybrid photocatalyst, biomimetic molecular cocatalysts, and semiconductor light harvester for artificial photosynthesis and therefore provide a promising approach for rational design and construction of highly efficient and stable artificial photosynthetic systems.

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Desulfovibrio desulfuricans iron hydrogenase: the structure shows unusual coordination to an active site Fe binuclear center

Cited by 1,350 publications

References 44 publications

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

The role of the maturase HydG in [FeFe]‐hydrogenase active site synthesis and assembly

Hybrid Artificial Photosynthetic Systems Comprising Semiconductors as Light Harvesters and Biomimetic Complexes as Molecular Cocatalysts

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