Regioselectivity of H Cluster Oxidation

Bruska, Marta K.; Stiebritz, Martin T.; Reiher, Markus

doi:10.1021/ja209165r

Cited by 52 publications

(84 citation statements)

References 87 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results suggested that O 2 induces degradation first of the cubane cluster while leaving the diiron unit largely intact [41][42]. A similar mechanism has been supported by DFT calculations [43]. A similar mechanism has been supported by DFT calculations [43].…”

Section: [Fefe]-hydrogenasessupporting

confidence: 57%

5 Metal centers in hydrogenase enzymes studied by X-ray spectroscopy

Haumann¹

2015

Biohydrogen

View full text Add to dashboard Cite

Michael Haumann Metal centers in hydrogenase enzymes studied by X-ray spectroscopyAbbreviations:EXAFS extended X-ray absorption fine structure FEL free electron (X-ray) laser NIS nuclear inelastic X-ray scattering MBH membrane-bound hydrogenase PH periplasmic hydrogenase RIXS resonant inelastic X-ray scattering RH regulatory hydrogenase SH soluble hydrogenase XANES X-ray absorption near edge structure XAE combined XAS and XES experiment XAS X-ray absorption spectroscopy XES X-ray emission spectroscopy XMCD X-ray magnetic circular dichroism

show abstract

Section: [Fefe]-hydrogenasessupporting

confidence: 57%

5 Metal centers in hydrogenase enzymes studied by X-ray spectroscopy

Haumann¹

2015

Biohydrogen

View full text Add to dashboard Cite

show abstract

“…Bonds that were cut, when the model was extracted from the crystal structure, were saturated with hydrogen atoms. Their bond lengths were adjusted to the same length as in ref 24, and both atoms of the bond were kept fixed during structure optimization to preserve the structural constraints of the protein matrix (fixed atoms are indicated in Figure 1). Calculations were carried out with version 6.3.1 of the Turbomole program package.…”

Section: Computational Methodologymentioning

confidence: 99%

Activation Barriers of Oxygen Transformation at the Active Site of [FeFe] Hydrogenases

2014

Self Cite

View full text Add to dashboard Cite

Oxygen activation at the active sites of [FeFe] hydrogenases has been proposed to be the initial step of irreversible oxygen-induced inhibition of these enzymes. On the basis of a first theoretical study into the thermodynamics of O2 activation [Inorg. Chem. 2009, 48, 7127] we here investigate the kinetics of possible reaction paths at the distal iron atom of the active site by means of density functional theory. A sequence of steps is proposed to either form a reactive oxygen species (ROS) or fully reduce O2 to water. In this reaction cascade, two branching points are identified where water formation directly competes with harmful oxygen activation reactions. The latter are water formation by O-O bond cleavage of a hydrogen peroxide-bound intermediate competing with H2O2 dissociation and CO2 formation by a putative iron-oxo species competing with protonation of the iron-oxo species to form a hydroxyo ligand. Furthermore, we show that proton transfer to activated oxygen is fast and that proton supply to the active site is vital to prevent ROS dissociation. If sufficiently many reduction equivalents are available, oxygen activation reactions are accelerated, and oxygen reduction to water becomes possible.

show abstract

“…According to X-ray absorption measurements, exposing the enzyme from Cr to O 2 damages the 4Fe4S subcluster; this suggested that O 2 binding to Fe d results in the formation of a reactive oxygen species (ROS) that diffuses towards the 4Fe4S subcluster and destroys it. 16,18 According to the DFT studies of Reiher 19,20 and Pachter, 21 this ROS could be the OOH radical or H 2 O 2 . However, this mechanism conflicts with a recent report according to which the O 2 -damaged enzyme from Cr harbors an intact 4Fe4S subsite and no 2Fe subcluster, and the observation that the O 2 -damaged enzyme is repaired upon insertion of a synthetic analogue of the 2Fe subcluster.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of O2 diffusion and reduction in FeFe hydrogenases

et al. 2016

View full text Add to dashboard Cite

FeFe hydrogenases are the most efficient H2 producing enzymes, but inactivation by O2 is an obstacle to using them in biotechnological devices. Here we combine electrochemistry, site-directed mutagenesis, molecular dynamics and quantum chemical calculations to uncover the molecular mechanism of O2 diffusion within the enzyme and its reactions at the active site. We find that the partial reversibility of the reaction with O2 results from the four-electron reduction of O2 to water. The third electron/proton transfer step is the bottleneck for water production, competing with formation of the highly reactive OH radical and hydroxylated cysteine, consistent with recent crystallographic evidence. The rapid delivery of electrons and protons to the active site is therefore crucial to prevent the accumulation of these aggressive species at prolonged O2 exposure. These findings should provide important clues for the design of hydrogenase mutants with increased resistance to oxidative damage.

show abstract

Regioselectivity of H Cluster Oxidation

Cited by 52 publications

References 87 publications

5 Metal centers in hydrogenase enzymes studied by X-ray spectroscopy

5 Metal centers in hydrogenase enzymes studied by X-ray spectroscopy

Activation Barriers of Oxygen Transformation at the Active Site of [FeFe] Hydrogenases

Mechanism of O2 diffusion and reduction in FeFe hydrogenases

Contact Info

Product

Resources

About