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Showing 1 to 20 of 34 for “"hydrogenases"”.
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Spectroscopic studies on hydrogenases
… is catalysed by a group of enzymes called hydrogenases. Members of this wide family of enzymes exhibit various properties, such as different activity rates, bias towards a specific direction of the catalytic reaction and a potential tolerance towards oxygen. Vibrational spectroscopy can be …
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Investigating [NiFe]-hydrogenases in γ-Proteobacteria
… family involved in hydrogen metabolism are Hydrogenases. These enzymes catalyse the reversible conversion of molecular hydrogen to protons and electrons (H2 ↔ 2H+ + 2e-). These enzymes have the potential to be utilised for biotechnological applications such as hydrogen fuel cells, but they …
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Diferrous Structural and Functional Models of the Iron-Only Hydrogenases
Low temperature IR spectroscopic studies show that the protonation of (Et4N)2[Fe2(S2C3H 6)(CN)2(CO)4] with HOTs gave Et4N[Fe 2(S2C3H6)(CN)(CNH)(CO)4]. Et4N[Fe2(S2C3H6)(CN)(CNH)(CO) 4] undergoes an approximate first-order decay to the hydride, Et 4N[HFe2(S2C3H6)(CN) 2(CO)4]. Addition of a second …
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Vibrational spectroscopic studies on [NiFe] hydrogenases: insights into structure and function
… is orchestrated by metalloenzymes known as hydrogenases, which operate with remarkable catalytic rates using exclusively nickel and/or iron metals. The discovery of hydrogenases has been a breakthrough towards novel catalytic strategies to replace noble metals like platinum. Additionally, …
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Modeling the Active Sites of [nickel-Iron]- and [iron-Iron]-Hydrogenases
While previous hydride-containing [FeFe]-hydrogenase models featured only bridging hydrides, we sought to prepare complexes of terminal hydrides that would be more relevant to mimicking this hydrogenase. Di-subferrous precursors, such as Fe2(S2C2H4)(CO)4 (PMe3)2, have been known for decades---well …
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Chemistry related to the actives sites of the [Fe]- and [FeFe]-hydrogenases
Hydrogenases are an important group of enzymes found in a range of microorganisms. There are three phylogenetically distinct classes of hydrogenase all of which feature iron-containing complexes. The work contained in this thesis has two main focuses: the synthesis and characterization of novel …
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Mixed-valence bimetallic dithiolates of iron, cobalt, and nickel and their relevance to the hydrogenases
… hydrogen. Nature utilizes metalloproteins called hydrogenases (H2ases) to efficiently interconvert protons and electrons with dihydrogen. Though this is one of the simplest possible reactions, it is of utmost importance for countless microorganisms. The performance of these enzymes exceeds that of …
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Biochemical and spectroscopic insights into peculiar active site structures and biosynthesis of O2-tolerant [NiFe]-hydrogenases
[NiFe]-hydrogenases are metalloenzymes catalyzing the reversible cleavage of H2 into two H+ and two e–. They are particularly interesting for clean and sustainable H2-based energy conversion approaches or the H2-driven regeneration of nucleotide cofactors. Their active site consists of a …
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Electron Transport in Methanosarcina: Pathway Heterogeneity Within the Genus
… Methanosarcina barkeri is known to utilize hydrogenases to transfer electrons from ferredoxin to methanophenazine. This thesis characterizes electron transport in the marine methanogen Methanosarcina acetivorans. Genomic comparison of hydrogenase gene clusters reveals that M. acetivorans …
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Hydrogen Production From Model Complexes of the [iron-Iron]- and [nickel-Iron]-Hydrogenase Active Sites
Unlike the [FeFe]-hydrogenases, model complexes for the [NiFe]-hydrogenases were unknown prior to the crystal structure in 1996. However, most synthetic efforts focused on structural models for the active site, and neglected the catalytically imperative hydride ligand. Thus, we sought a nickel-iron …
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Hydrogen production from model complexes of the [FeFe]- and [NiFe]-hydrogenase active sites
… direction toward this goal, as enzymes called hydrogenases evolved several billion years ago to utilize molecular hydrogen as a fuel. The [FeFe]-hydrogenases predominately function to produce hydrogen from protons and electrons, while the [NiFe]-hydrogenases function to oxidize hydrogen. The …
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Hydrogenase utilization and regulation in species of methanosarcina
… branch of methanogenesis required active hydrogenases, and that M. barkeri was potentially able to regulate gene expression based on the redox state of coenzyme F420. In Chapter 3, I explored the regulation of hydrogenases in Methanosarcina acetivorans, a species that is incapable of …
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Synthetic models of [FeFe]-hydrogenase: case studies utilizing azadithiolate and nitrosyl coligands
Hydrogenases are enzymes that catalyze the reversible interconversion of protons, electrons, and dihydrogen (2H+ + 2e− <-> H2). Because of the potential utility of H2 as an energy carrier, the detailed understanding of hydrogenases has received considerable attention and funding. In particular, …
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Production of a soluble hydrogenase from R. Eutropha H16
Hydrogenases are metalloenzymes that reversibly catalyse the oxidation or production of molecular hydrogen (H2) and are generally classified by the structure of the catalytic site. From a biotechnology perspective, hydrogenases have been extensively studied with a view to their potential …
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Proton-coupled electron transfer reactions in bio-inspired catalysis
… of guiding design principles. In nature, hydrogenases are the most active catalysts for hydrogen production, with rates and overpotentials comparable to leading, synthetic Pt catalysts while utilizing earth abundant metal centers in their active sites. Density functional theory …
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Studies on the Methylcoenzyme M Methylreductase System of Methanobacterium Thermoautotrophicum
… One of them, called A4, contained one of the hydrogenases of Methanobacterium. The other, called component A3 per se, consisted of an FeS protein with a molecular weight of 500,000. A model for the functioning of the methylcoenzyme M methylreductase system, including components A1, A2, A3, A4, …
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Biohydrogen as a Fuel: Understanding and Engineering Hydrogenase Enzymes for Biotechnological Applications
… for microbial H2 evolution are called hydrogenases. The model organism Escherichia coli produces H2 during mixed acid fermentation by the action of it native hydrogenases. However, the natural level of H2 produced is too low to meet current industrial demand for H2 or any future uses as …
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Modeling The Active Site Of [NiFe]-Hydrogenase
The hydrogenases are metalloenzymes that act to catalytically interconvert dihydrogen with protons and electrons. Although there are three classes of hydrogenases that are known, the focus of this research will be on the first hydrogenase to be evolved, the [NiFe]-hydrogenase, which contains a …
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A combined approach of electronic structure calculations and spectroscopy for elucidating reaction mechanisms in organic and bioinorganic systems
… the protonation mechanism of [FeFe]-hydrogenases, transition state theory is used and the energetics of reaction pathways leading to terminal and bridging hydrides calculated and compared. NIS demonstrates great potential for characterising the [FeFe]-hydrogenase mimics. In order to …
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