A Trinuclear [NiFe] Cluster Exhibiting Structural and Functional Key Features of [NiFe] Hydrogenases

Sellmann, Dieter; Lauderbach, Frank; Geipel, Franz; Heinemann, Frank W.; Moll, Matthias

doi:10.1002/anie.200353440

Cited by 46 publications

(57 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, the FTIR spectra of this reduced mutant are also in agreement with the spectral heterogeneity found by EPR. DISCUSSION X-ray diffraction data (14,23,29,30), x-ray absorption spectroscopy (28), EPR (27,32), model complexes chemistry (25,26), and theoretical calculations (24,31) support that one of the terminal cysteine ligands of the active site nickel atom (Cys-543 in D. fructosovorans numeration) participates in the heterolytic splitting of molecular hydrogen by acting as the base for proton binding. A conserved glutamic residue (Glu-25 or Glu-18 in D. fructosovorans or D. gigas numeration, respectively) has been proposed as the next step in the proton transfer pathway between the active site and the protein environment in [NiFe] hydrogenases because its carboxylic group forms a hydrogen bond with the mentioned terminal cysteine residue, and carboxylic groups have an adequate pK a for proton transport inside proteins (14, 22, 23).…”

Section: Resultsmentioning

confidence: 99%

A Glutamate Is the Essential Proton Transfer Gate during the Catalytic Cycle of the [NiFe] Hydrogenase

Dementin

Burlat

Lacey

et al. 2004

Journal of Biological Chemistry

139

185

View full text Add to dashboard Cite

Kinetic, EPR, and Fourier transform infrared spectroscopic analysis of Desulfovibrio fructosovorans [NiFe]hydrogenase mutants targeted to Glu-25 indicated that this amino acid participates in proton transfer between the active site and the protein surface during the catalytic cycle. Replacement of that glutamic residue by a glutamine did not modify the spectroscopic properties of the enzyme but cancelled the catalytic activity except the para-H 2 /ortho-H 2 conversion. This mutation impaired the fast proton transfer from the active site that allows high turnover numbers for the oxidation of hydrogen. Replacement of the glutamic residue by the shorter aspartic acid slowed down this proton transfer, causing a significant decrease of H 2 oxidation and hydrogen isotope exchange activities, but did not change the para-H 2 /ortho-H 2 conversion activity. The spectroscopic properties of this mutant were totally different, especially in the reduced state in which a non-photosensitive nickel EPR spectrum was obtained.Many microorganisms use molecular hydrogen in their metabolic routes as an energy source or for evacuating an excess of electrons. The enzymes that catalyze reversibly the conversion of molecular hydrogen to two electrons and two protons are known as hydrogenases. Although this is the simplest chemical reaction, the catalytic mechanism of these enzymes is quite complicated, and its details are still a matter of debate (1). Hydrogen isotope exchange experiments indicate that the H 2 cleavage reaction is heterolytic; thus, a hydride and a proton are formed in the first step (2, 3). In the second step, the two electrons of the hydride are extracted, and a second proton is formed. Subsequently, the two electrons have to be transported, via the intramolecular electron transfer chain, from the active site to the redox partner of the hydrogenase (a redox protein or NAD ϩ (P)) in vivo, or a redox dye in vitro; the two protons have to be transferred to the protein environment as well. These steps are reversed in the case of H 2 production activity (1).How do all these steps take place in hydrogenases? These proteins are metalloenzymes that all contain iron, and in many cases, also nickel. The crystallographic structures of several [Fe] hydrogenases (4, 5) and [NiFe] hydrogenases (6, 7) have been obtained by x-ray diffraction studies. In both types of enzymes, the active site is a deeply buried bimetallic center, in which the metals are bridged by thiol groups and have CO and CN Ϫ as ligands. This type of coordination favors the binding of molecular hydrogen or hydride to the active site (1, 8). The crystal structures also indicate that Fe-S clusters are located between the active site and the protein surface, which are thought to form the intramolecular electron pathway in the H 2 production/oxidation mechanism (9). In [NiFe] hydrogenases, one nickel and one iron atom form the bimetallic center. The nickel is coordinated to four cysteine ligands via their thiol groups. Two of them are terminal ligands, and the other...

show abstract

Section: Resultsmentioning

confidence: 99%

A Glutamate Is the Essential Proton Transfer Gate during the Catalytic Cycle of the [NiFe] Hydrogenase

Dementin

Burlat

Lacey

et al. 2004

Journal of Biological Chemistry

139

185

View full text Add to dashboard Cite

show abstract

“…[2,14Ϫ18] However, so far only one heterodimetallic nickelϪiron complex that has an S 4 coordination environment around the nickel centre has been reported. [19] In this paper, we describe the synthesis of new heterometallic nickelϪiron complexes, starting from a nickel complex with an S 4 coordination environment. [20] Results and Discussion (4) was performed in chloroform and the reaction mixture was cooled to 273 K in the absence of light.…”

Section: Introductionmentioning

confidence: 99%

“…The coordination environment around the nickel ion has a small tetrahedral distortion, with an interplanar angle of 5.75(2)°between the planes S(6)ϪNi(1)ϪS(9) and S(16)Ϫ Ni(1)ϪS (19).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterisation of New Nickel‐Iron Complexes with an S₄ Coordination Environment around the Nickel Centre

et al. 2003

View full text Add to dashboard Cite

The nickel complex [Ni(xbsms) crystallises in the monoclinic space group P2 1 /c, with the dimer located on the inversion centre. The nickel ions are in a square-planar S 2 SЈ 2 environment, comprised of two thioether and two thiolate sulfur atoms. The thiolate sulfur atoms form a bridge between the nickel ion and the iron centre. The iron ions are in a pseudo square-pyramidal S 2 Cl 3 environment, with two chloride ions forming a bridge between the two iron centres.

show abstract

“…[11] Moreover, the latter remarkably reduces protons to dihydrogen, affording the cationic species [('S 2 '){Ni(PMe 3 )} 2 Fe(CO)('S 2 ') 2 ]…”

Section: Introductionmentioning

confidence: 99%

“…bis(2-mercaptophenyl)sulfide(2Ϫ)] [10] and [('S 2 '){Ni(PMe 3 )} 2 Fe(CO)('S 2 ') 2 ]. [11] Moreover, the latter remarkably reduces protons to dihydrogen, affording the cationic species [('S 2 '){Ni(PMe 3 )} 2 Fe(CO)('S 2 ') 2 ]…”

Section: Introductionmentioning

confidence: 99%

Trinuclear [NiFe] Clusters as Structural Models for [NiFe] Hydrogenase Active Sites

2005

Self Cite

View full text Add to dashboard Cite

Abstract[Fe(CH3COCH=CHPh)(CO)3] reacts with [Ni(‘S4’)]x (x = 1, 2) or [Ni(‘S4C3Me2’)] [‘S4’2− = 1,2‐bis(2‐mercaptophenylthio)ethane(2‐),‘S4C3Me2’2− = 1,3‐bis(2‐mercaptophenylthio)‐2,2‐dimethylpropane(2‐)] to afford trinuclear [NiFe] clusters [Ni(‘S4’){Fe(CO)3}2] (1) and [Ni(‘S4C3Me2’){Fe(CO)3}2] (2) and the dinuclear FeIIFe0 complex [Fe(CO)(‘S4C3Me2’)Fe(CO)3] (3). Clusters 1 and 2 have Ni−Fe bond lengths similar to those of active or reduced states of [NiFe] hydrogenases, a sulfur‐dominated coordination sphere of Ni and iron‐bound CO. Therefore, 1 and 2 may serve as structural model complexes for the [NiFe] hydrogenase active site. Combination of the ‘S4C3Me2’ ligand with FeCl2·4H2O yielded [Fe(‘S4C3Me2’)]2 (4), the dinuclearity of which suggests that the ‘S4C3Me2’ ligand is less flexible than its ethylene‐bridged derivative, which affords a tetrameric [Fe(‘S4’)]4 complex reported earlier. Compound 4 reacts with 2 equiv. of CO to give [Fe(CO)(‘S4C3Me2’)]2 (5), which like 4 is only sparingly soluble in all common organic solvents. Complex 5 easily loses CO even if stored in the solid state. [Fe(CH3COCH=CHPh)(CO)3] reacts with 5 to afford 3 as the only product. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

show abstract

A Trinuclear [NiFe] Cluster Exhibiting Structural and Functional Key Features of [NiFe] Hydrogenases

Cited by 46 publications

References 27 publications

A Glutamate Is the Essential Proton Transfer Gate during the Catalytic Cycle of the [NiFe] Hydrogenase

A Glutamate Is the Essential Proton Transfer Gate during the Catalytic Cycle of the [NiFe] Hydrogenase

Synthesis and Characterisation of New Nickel‐Iron Complexes with an S₄ Coordination Environment around the Nickel Centre

Trinuclear [NiFe] Clusters as Structural Models for [NiFe] Hydrogenase Active Sites

Contact Info

Product

Resources

About

A Trinuclear [NiFe] Cluster Exhibiting Structural and Functional Key Features of [NiFe] Hydrogenases

Cited by 46 publications

References 27 publications

A Glutamate Is the Essential Proton Transfer Gate during the Catalytic Cycle of the [NiFe] Hydrogenase

A Glutamate Is the Essential Proton Transfer Gate during the Catalytic Cycle of the [NiFe] Hydrogenase

Synthesis and Characterisation of New Nickel‐Iron Complexes with an S4 Coordination Environment around the Nickel Centre

Trinuclear [NiFe] Clusters as Structural Models for [NiFe] Hydrogenase Active Sites

Contact Info

Product

Resources

About

Synthesis and Characterisation of New Nickel‐Iron Complexes with an S₄ Coordination Environment around the Nickel Centre