1
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Cabotaje P, Walter K, Zamader A, Huang P, Ho F, Land H, Senger M, Berggren G. Probing Substrate Transport Effects on Enzymatic Hydrogen Catalysis: An Alternative Proton Transfer Pathway in Putatively Sensory [FeFe] Hydrogenase. ACS Catal 2023; 13:10435-10446. [PMID: 37560193 PMCID: PMC10407848 DOI: 10.1021/acscatal.3c02314] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 07/04/2023] [Indexed: 08/11/2023]
Abstract
[FeFe] hydrogenases, metalloenzymes catalyzing proton/dihydrogen interconversion, have attracted intense attention due to their remarkable catalytic properties and (bio-)technological potential for a future hydrogen economy. In order to unravel the factors enabling their efficient catalysis, both their unique organometallic cofactors and protein structural features, i.e., "outer-coordination sphere" effects have been intensively studied. These structurally diverse enzymes are divided into distinct phylogenetic groups, denoted as Group A-D. Prototypical Group A hydrogenases display high turnover rates (104-105 s-1). Conversely, the sole characterized Group D representative, Thermoanaerobacter mathranii HydS (TamHydS), shows relatively low catalytic activity (specific activity 10-1 μmol H2 mg-1 min-1) and has been proposed to serve a H2-sensory function. The various groups of [FeFe] hydrogenase share the same catalytic cofactor, the H-cluster, and the structural factors causing the diverging reactivities of Group A and D remain to be elucidated. In the case of the highly active Group A enzymes, a well-defined proton transfer pathway (PTP) has been identified, which shuttles H+ between the enzyme surface and the active site. In Group D hydrogenases, this conserved pathway is absent. Here, we report on the identification of highly conserved amino acid residues in Group D hydrogenases that constitute a possible alternative PTP. We varied two proposed key amino acid residues of this pathway (E252 and E289, TamHydS numbering) via site-directed mutagenesis and analyzed the resulting variants via biochemical and spectroscopic methods. All variants displayed significantly decreased H2-evolution and -oxidation activities. Additionally, the variants showed two redox states that were not characterized previously. These findings provide initial evidence that these amino acid residues are central to the putative PTP of Group D [FeFe] hydrogenase. Since the identified residues are highly conserved in Group D exclusively, our results support the notion that the PTP is not universal for different phylogenetic groups in [FeFe] hydrogenases.
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Affiliation(s)
| | | | - Afridi Zamader
- Molecular Biomimetics, Department
of Chemistry, Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
| | - Ping Huang
- Molecular Biomimetics, Department
of Chemistry, Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
| | - Felix Ho
- Molecular Biomimetics, Department
of Chemistry, Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
| | - Henrik Land
- Molecular Biomimetics, Department
of Chemistry, Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
| | - Moritz Senger
- Molecular Biomimetics, Department
of Chemistry, Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
| | - Gustav Berggren
- Molecular Biomimetics, Department
of Chemistry, Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
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2
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Stripp ST, Duffus BR, Fourmond V, Léger C, Leimkühler S, Hirota S, Hu Y, Jasniewski A, Ogata H, Ribbe MW. Second and Outer Coordination Sphere Effects in Nitrogenase, Hydrogenase, Formate Dehydrogenase, and CO Dehydrogenase. Chem Rev 2022; 122:11900-11973. [PMID: 35849738 PMCID: PMC9549741 DOI: 10.1021/acs.chemrev.1c00914] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Gases like H2, N2, CO2, and CO are increasingly recognized as critical feedstock in "green" energy conversion and as sources of nitrogen and carbon for the agricultural and chemical sectors. However, the industrial transformation of N2, CO2, and CO and the production of H2 require significant energy input, which renders processes like steam reforming and the Haber-Bosch reaction economically and environmentally unviable. Nature, on the other hand, performs similar tasks efficiently at ambient temperature and pressure, exploiting gas-processing metalloenzymes (GPMs) that bind low-valent metal cofactors based on iron, nickel, molybdenum, tungsten, and sulfur. Such systems are studied to understand the biocatalytic principles of gas conversion including N2 fixation by nitrogenase and H2 production by hydrogenase as well as CO2 and CO conversion by formate dehydrogenase, carbon monoxide dehydrogenase, and nitrogenase. In this review, we emphasize the importance of the cofactor/protein interface, discussing how second and outer coordination sphere effects determine, modulate, and optimize the catalytic activity of GPMs. These may comprise ionic interactions in the second coordination sphere that shape the electron density distribution across the cofactor, hydrogen bonding changes, and allosteric effects. In the outer coordination sphere, proton transfer and electron transfer are discussed, alongside the role of hydrophobic substrate channels and protein structural changes. Combining the information gained from structural biology, enzyme kinetics, and various spectroscopic techniques, we aim toward a comprehensive understanding of catalysis beyond the first coordination sphere.
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Affiliation(s)
- Sven T Stripp
- Freie Universität Berlin, Experimental Molecular Biophysics, Berlin 14195, Germany
| | | | - Vincent Fourmond
- Laboratoire de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, Institut Microbiologie, Bioénergies et Biotechnologie, CNRS, Aix Marseille Université, Marseille 13402, France
| | - Christophe Léger
- Laboratoire de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, Institut Microbiologie, Bioénergies et Biotechnologie, CNRS, Aix Marseille Université, Marseille 13402, France
| | - Silke Leimkühler
- University of Potsdam, Molecular Enzymology, Potsdam 14476, Germany
| | - Shun Hirota
- Nara Institute of Science and Technology, Division of Materials Science, Graduate School of Science and Technology, Nara 630-0192, Japan
| | - Yilin Hu
- Department of Molecular Biology & Biochemistry, University of California, Irvine, California 92697-3900, United States
| | - Andrew Jasniewski
- Department of Molecular Biology & Biochemistry, University of California, Irvine, California 92697-3900, United States
| | - Hideaki Ogata
- Nara Institute of Science and Technology, Division of Materials Science, Graduate School of Science and Technology, Nara 630-0192, Japan.,Hokkaido University, Institute of Low Temperature Science, Sapporo 060-0819, Japan.,Graduate School of Science, University of Hyogo, Hyogo 678-1297, Japan
| | - Markus W Ribbe
- Department of Molecular Biology & Biochemistry, University of California, Irvine, California 92697-3900, United States.,Department of Chemistry, University of California, Irvine, California 92697-2025, United States
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3
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Wiedner ES, Appel AM, Raugei S, Shaw WJ, Bullock RM. Molecular Catalysts with Diphosphine Ligands Containing Pendant Amines. Chem Rev 2022; 122:12427-12474. [PMID: 35640056 DOI: 10.1021/acs.chemrev.1c01001] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Pendant amines play an invaluable role in chemical reactivity, especially for molecular catalysts based on earth-abundant metals. As inspired by [FeFe]-hydrogenases, which contain a pendant amine positioned for cooperative bifunctionality, synthetic catalysts have been developed to emulate this multifunctionality through incorporation of a pendant amine in the second coordination sphere. Cyclic diphosphine ligands containing two amines serve as the basis for a class of catalysts that have been extensively studied and used to demonstrate the impact of a pendant base. These 1,5-diaza-3,7-diphosphacyclooctanes, now often referred to as "P2N2" ligands, have profound effects on the reactivity of many catalysts. The resulting [Ni(PR2NR'2)2]2+ complexes are electrocatalysts for both the oxidation and production of H2. Achieving the optimal benefit of the pendant amine requires that it has suitable basicity and is properly positioned relative to the metal center. In addition to the catalytic efficacy demonstrated with [Ni(PR2NR'2)2]2+ complexes for the oxidation and production of H2, catalysts with diphosphine ligands containing pendant amines have also been demonstrated for several metals for many different reactions, both in solution and immobilized on surfaces. The impact of pendant amines in catalyst design continues to expand.
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4
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Soucy TL, Dean WS, Zhou J, Rivera Cruz KE, McCrory CCL. Considering the Influence of Polymer-Catalyst Interactions on the Chemical Microenvironment of Electrocatalysts for the CO 2 Reduction Reaction. Acc Chem Res 2022; 55:252-261. [PMID: 35044745 DOI: 10.1021/acs.accounts.1c00633] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The electrochemical CO2 reduction reaction (CO2RR) is an attractive method for capturing intermittent renewable energy sources in chemical bonds, and converting waste CO2 into value-added products with a goal of carbon neutrality. Our group has focused on developing polymer-encapsulated molecular catalysts, specifically cobalt phthalocyanine (CoPc), as active and selective electrocatalysts for the CO2RR. When CoPc is adsorbed onto a carbon electrode and encapsulated in poly(4-vinylpyridine) (P4VP), its activity and reaction selectivity over the competitive hydrogen evolution reaction (HER) are enhanced by three synergistic effects: a primary axial coordination effect, a secondary reaction intermediate stabilization effect, and an outer-coordination proton transport effect. We have studied multiple aspects of this system using electrochemical, spectroscopic, and computational tools. Specifically, we have used X-ray absorption spectroscopy measurements to confirm that the pyridyl residues from the polymer are axially coordinated to the CoPc metal center, and we have shown that increasing the σ-donor ability of nitrogen-containing axial ligands results in increased activity for the CO2RR. Using proton inventory studies, we showed that proton delivery in the CoPc-P4VP system is controlled via a proton relay through the polymer matrix. Additionally, we studied the effect of catalyst, polymer, and graphite powder loading on CO2RR activity and determined best practices for incorporating carbon supports into catalyst-polymer composite films.In this Account, we describe these studies in detail, organizing our discussion by three types of microenvironmental interactions that affect the catalyst performance: ligand effects of the primary and secondary sphere, substrate transport of protons and CO2, and charge transport from the electrode surface to the catalyst sites. Our work demonstrates that careful electroanalytical study and interpretation can be valuable in developing a robust and comprehensive understanding of catalyst performance. In addition to our work with polymer encapsulated CoPc, we provide examples of similar surface-adsorbed molecular and solid-state systems that benefit from interactions between active catalytic sites and a polymer system. We also compare the activity results from our systems to other results in the CoPc literature, and other examples of molecular CO2RR catalysts on modified electrode surfaces. Finally, we speculate how the insights gained from studying CoPc could guide the field in designing other polymer-electrocatalyst systems. As CO2RR technologies become commercially viable and expand into the space of flow cells and gas-diffusion electrodes, we propose that overall device efficiency may benefit from understanding and promoting synergistic polymer-encapsulation effects in the microenvironment of these catalyst systems.
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Affiliation(s)
- Taylor L. Soucy
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - William S. Dean
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Jukai Zhou
- Macromolecular Science and Engineering Program, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Kevin E. Rivera Cruz
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Charles C. L. McCrory
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
- Macromolecular Science and Engineering Program, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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5
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Kleinhaus JT, Wittkamp F, Yadav S, Siegmund D, Apfel UP. [FeFe]-Hydrogenases: maturation and reactivity of enzymatic systems and overview of biomimetic models. Chem Soc Rev 2021; 50:1668-1784. [DOI: 10.1039/d0cs01089h] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
[FeFe]-hydrogenases recieved increasing interest in the last decades. This review summarises important findings regarding their enzymatic reactivity as well as inorganic models applied as electro- and photochemical catalysts.
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Affiliation(s)
| | | | - Shanika Yadav
- Inorganic Chemistry I
- Ruhr University Bochum
- 44801 Bochum
- Germany
| | - Daniel Siegmund
- Department of Electrosynthesis
- Fraunhofer UMSICHT
- 46047 Oberhausen
- Germany
| | - Ulf-Peter Apfel
- Inorganic Chemistry I
- Ruhr University Bochum
- 44801 Bochum
- Germany
- Department of Electrosynthesis
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6
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Lukoyanov DA, Yang ZY, Dean DR, Seefeldt LC, Raugei S, Hoffman BM. Electron Redistribution within the Nitrogenase Active Site FeMo-Cofactor During Reductive Elimination of H 2 to Achieve N≡N Triple-Bond Activation. J Am Chem Soc 2020; 142:21679-21690. [PMID: 33326225 DOI: 10.1021/jacs.0c07914] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitrogen fixation by nitrogenase begins with the accumulation of four reducing equivalents at the active-site FeMo-cofactor (FeMo-co), generating a state (denoted E4(4H)) with two [Fe-H-Fe] bridging hydrides. Recently, photolytic reductive elimination (re) of the E4(4H) hydrides showed that enzymatic re of E4(4H) hydride yields an H2-bound complex (E4(H2,2H)), in a process corresponding to a formal 2-electron reduction of the metal-ion core of FeMo-co. The resulting electron-density redistribution from Fe-H bonds to the metal ions themselves enables N2 to bind with concomitant H2 release, a process illuminated here by QM/MM molecular dynamics simulations. What is the nature of this redistribution? Although E4(H2,2H) has not been trapped, cryogenic photolysis of E4(4H) provides a means to address this question. Photolysis of E4(4H) causes hydride-re with release of H2, generating doubly reduced FeMo-co (denoted E4(2H)*), the extreme limit of the electron-density redistribution upon formation of E4(H2,2H). Here we examine the doubly reduced FeMo-co core of the E4(2H)* limiting-state by 1H, 57Fe, and 95Mo ENDOR to illuminate the partial electron-density redistribution upon E4(H2,2H) formation during catalysis, complementing these results with corresponding DFT computations. Inferences from the E4(2H)* ENDOR results as extended by DFT computations include (i) the Mo-site participates negligibly, and overall it is unlikely that Mo changes valency throughout the catalytic cycle; and (ii) two distinctive E4(4H) 57Fe signals are suggested as associated with structurally identified "anchors" of one bridging hydride, two others with identified anchors of the second, with NBO-analysis further identifying one anchor of each hydride as a major recipient of electrons released upon breaking Fe-H bonds.
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Affiliation(s)
- Dmitriy A Lukoyanov
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Zhi-Yong Yang
- Department of Chemistry and Biocemistry, Utah State University, Logan, Utah 84322, United States
| | - Dennis R Dean
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
| | - Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Simone Raugei
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Brian M Hoffman
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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7
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Land H, Senger M, Berggren G, Stripp ST. Current State of [FeFe]-Hydrogenase Research: Biodiversity and Spectroscopic Investigations. ACS Catal 2020. [DOI: 10.1021/acscatal.0c01614] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Henrik Land
- Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala 75120, Sweden
| | - Moritz Senger
- Physical Chemistry, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala 75120, Sweden
- Bioinorganic Spectroscopy, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Gustav Berggren
- Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala 75120, Sweden
| | - Sven T. Stripp
- Bioinorganic Spectroscopy, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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8
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Punt PM, Stratmann LM, Sevim S, Knauer L, Strohmann C, Clever GH. Heteroleptic Coordination Environments in Metal-Mediated DNA G-Quadruplexes. Front Chem 2020; 8:26. [PMID: 32064249 PMCID: PMC7000376 DOI: 10.3389/fchem.2020.00026] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 01/09/2020] [Indexed: 12/28/2022] Open
Abstract
The presence of metal centers with often highly conserved coordination environments is crucial for roughly half of all proteins, having structural, regulatory, or enzymatic function. To understand and mimic the function of metallo-enzymes, bioinorganic chemists pursue the challenge of synthesizing model compounds with well-defined, often heteroleptic metal sites. Recently, we reported the design of tailored homoleptic coordination environments for various transition metal cations based on unimolecular DNA G-quadruplex structures, templating the regioselective positioning of imidazole ligandosides LI. Here, we expand this modular system to more complex, heteroleptic coordination environments by combining LI with a new benzoate ligandoside LB within the same oligonucleotide. The modifications still allow the correct folding of parallel tetramolecular and antiparallel unimolecular G-quadruplexes. Interestingly, the incorporation of LB results in strong destabilization expressed in lower thermal denaturation temperatures Tm. While no transition metal cations could be bound by G-quadruplexes containing only LB, heteroleptic derivatives containing both LI and LB were found to complex CuII, NiII, and ZnII. Especially in case of CuII we found strong stabilizations of up to ΔTm = +34°C. The here shown system represents an important step toward the design of more complex coordination environments inside DNA scaffolds, promising to culminate in the preparation of functional metallo-DNAzymes.
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Affiliation(s)
- Philip M Punt
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
| | - Lukas M Stratmann
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
| | - Sinem Sevim
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
| | - Lena Knauer
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
| | - Carsten Strohmann
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
| | - Guido H Clever
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
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9
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Senger M, Eichmann V, Laun K, Duan J, Wittkamp F, Knör G, Apfel UP, Happe T, Winkler M, Heberle J, Stripp ST. How [FeFe]-Hydrogenase Facilitates Bidirectional Proton Transfer. J Am Chem Soc 2019; 141:17394-17403. [PMID: 31580662 PMCID: PMC6823627 DOI: 10.1021/jacs.9b09225] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Hydrogenases are metalloenzymes that
catalyze the conversion of
protons and molecular hydrogen, H2. [FeFe]-hydrogenases
show particularly high rates of hydrogen turnover and have inspired
numerous compounds for biomimetic H2 production. Two decades
of research on the active site cofactor of [FeFe]-hydrogenases have
put forward multiple models of the catalytic proceedings. In comparison,
our understanding of proton transfer is poor. Previously, residues
were identified forming a hydrogen-bonding network between active
site cofactor and bulk solvent; however, the exact mechanism of catalytic
proton transfer remained inconclusive. Here, we employ in
situ infrared difference spectroscopy on the [FeFe]-hydrogenase
from Chlamydomonas reinhardtii evaluating dynamic
changes in the hydrogen-bonding network upon photoreduction. While
proton transfer appears to be impaired in the oxidized state (Hox), the presented data support continuous proton transfer
in the reduced state (Hred). Our analysis allows for
a direct, molecular unique assignment to individual amino acid residues.
We found that transient protonation changes of glutamic acid residue
E141 and, most notably, arginine R148 facilitate bidirectional proton
transfer in [FeFe]-hydrogenases.
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Affiliation(s)
- Moritz Senger
- Experimental Molecular Biophysics, Department of Physics , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Viktor Eichmann
- Experimental Molecular Biophysics, Department of Physics , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Konstantin Laun
- Experimental Molecular Biophysics, Department of Physics , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | | | | | - Günther Knör
- Institute of Inorganic Chemistry , Johannes Kepler Universität Linz , Altenberger Straße 69 , 4040 Linz , Austria
| | | | | | | | - Joachim Heberle
- Experimental Molecular Biophysics, Department of Physics , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Sven Timo Stripp
- Experimental Molecular Biophysics, Department of Physics , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
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10
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Punt PM, Clever GH. Tailored Transition-Metal Coordination Environments in Imidazole-Modified DNA G-Quadruplexes. Chemistry 2019; 25:13987-13993. [PMID: 31468606 PMCID: PMC6899475 DOI: 10.1002/chem.201903445] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/28/2019] [Indexed: 12/18/2022]
Abstract
Two types of imidazole ligands were introduced both at the end of tetramolecular and into the loop region of unimolecular DNA G‐quadruplexes. The modified oligonucleotides were shown to complex a range of different transition‐metal cations including NiII, CuII, ZnII and CoII, as indicated by UV/Vis absorption spectroscopy and ion mobility mass spectrometry. Molecular dynamics simulations were performed to obtain structural insight into the investigated systems. Variation of ligand number and position in the loop region of unimolecular sequences derived from the human telomer region (htel) allows for a controlled design of distinct coordination environments with fine‐tuned metal affinities. It is shown that CuII, which is typically square‐planar coordinated, has a higher affinity for systems offering four ligands, whereas NiII prefers G‐quadruplexes with six ligands. Likewise, the positioning of ligands in a square‐planar versus tetrahedral fashion affects binding affinities of CuII and ZnII cations, respectively. Gaining control over ligand arrangement patterns will spur the rational development of transition‐metal‐modified DNAzymes. Furthermore, this method is suited to combine different types of ligands, for example, those typically found in metalloenzymes, inside a single DNA architecture.
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Affiliation(s)
- Philip M Punt
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Straße 6, 44227, Dortmund, Germany
| | - Guido H Clever
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Straße 6, 44227, Dortmund, Germany
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11
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Kumar N, Darmon JM, Weiss CJ, Helm ML, Raugei S, Morris Bullock R. Outer Coordination Sphere Proton Relay Base and Proximity Effects on Hydrogen Oxidation with Iron Electrocatalysts. Organometallics 2019. [DOI: 10.1021/acs.organomet.8b00805] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Neeraj Kumar
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-12, Richland, Washington 99352, United States
| | - Jonathan M. Darmon
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-12, Richland, Washington 99352, United States
| | - Charles J. Weiss
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-12, Richland, Washington 99352, United States
| | - Monte L. Helm
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-12, Richland, Washington 99352, United States
| | - Simone Raugei
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-12, Richland, Washington 99352, United States
| | - R. Morris Bullock
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-12, Richland, Washington 99352, United States
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12
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Abstract
Hydrogenases catalyze the simple yet important interconversion between H2 and protons and electrons. Found throughout prokaryotes, lower eukaryotes, and archaea, hydrogenases are used for a variety of redox and signaling purposes and are found in many different forms. This diverse group of metalloenzymes is divided into [NiFe], [FeFe], and [Fe] variants, based on the transition metal contents of their active sites. A wide array of biochemical and spectroscopic methods has been used to elucidate hydrogenases, and this along with a general description of the main enzyme types and catalytic mechanisms is discussed in this chapter.
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13
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Duan J, Senger M, Esselborn J, Engelbrecht V, Wittkamp F, Apfel UP, Hofmann E, Stripp ST, Happe T, Winkler M. Crystallographic and spectroscopic assignment of the proton transfer pathway in [FeFe]-hydrogenases. Nat Commun 2018; 9:4726. [PMID: 30413719 PMCID: PMC6226526 DOI: 10.1038/s41467-018-07140-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 10/18/2018] [Indexed: 11/29/2022] Open
Abstract
The unmatched catalytic turnover rates of [FeFe]-hydrogenases require an exceptionally efficient proton-transfer (PT) pathway to shuttle protons as substrates or products between bulk water and catalytic center. For clostridial [FeFe]-hydrogenase CpI such a pathway has been proposed and analyzed, but mainly on a theoretical basis. Here, eleven enzyme variants of two different [FeFe]-hydrogenases (CpI and HydA1) with substitutions in the presumptive PT-pathway are examined kinetically, spectroscopically, and crystallographically to provide solid experimental proof for its role in hydrogen-turnover. Targeting key residues of the PT-pathway by site directed mutagenesis significantly alters the pH-activity profile of these variants and in presence of H2 their cofactor is trapped in an intermediate state indicative of precluded proton-transfer. Furthermore, crystal structures coherently explain the individual levels of residual activity, demonstrating e.g. how trapped H2O molecules rescue the interrupted PT-pathway. These features provide conclusive evidence that the targeted positions are indeed vital for catalytic proton-transfer. [FeFe]-hydrogenases catalyze H2-evolution and -oxidation at very high turnover-rates. Here the authors provide experimental evidence for the proposed proton-transfer (PT) pathway by kinetically, spectroscopically, and crystallographically characterizing eleven mutants from the two [FeFe]-hydrogenases CpI and HydA1.
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Affiliation(s)
- Jifu Duan
- Department of Plant Biochemistry, Photobiotechnology, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Moritz Senger
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Julian Esselborn
- Department of Plant Biochemistry, Photobiotechnology, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Vera Engelbrecht
- Department of Plant Biochemistry, Photobiotechnology, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Florian Wittkamp
- Department of Chemistry and Biochemistry, Inorganic Chemistry Ι, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Ulf-Peter Apfel
- Department of Chemistry and Biochemistry, Inorganic Chemistry Ι, Ruhr-Universität Bochum, 44801, Bochum, Germany.,Fraunhofer UMSICHT, Osterfelder Straße, 346047, Oberhausen, Germany
| | - Eckhard Hofmann
- Department of Biophysics, Protein Crystallography, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Sven T Stripp
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Thomas Happe
- Department of Plant Biochemistry, Photobiotechnology, Ruhr-Universität Bochum, 44801, Bochum, Germany.
| | - Martin Winkler
- Department of Plant Biochemistry, Photobiotechnology, Ruhr-Universität Bochum, 44801, Bochum, Germany.
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14
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Abstract
Over the past two decades, the bioinorganic chemistry of hydrogenases has attracted much interest from basic and applied research. Hydrogenases are highly efficient metalloenzymes that catalyze the reversible reduction of protons to molecular hydrogen (H2) in all domains of life. Their iron- and nickel-based cofactors represent promising blueprints for the design of biomimetic, synthetic catalysts. In this Account, we address the molecular proceedings of hydrogen turnover with [FeFe]-hydrogenases. The active site cofactor of [FeFe]-hydrogenases ("H-cluster") comprises a unique diiron complex linked to a [4Fe-4S] cluster via a single cysteine. Since it was discovered that a synthetic analogue of the diiron site can be incorporated into apoprotein in vitro to yield active enzyme, significant progress has been made toward a comprehensive understanding of hydrogenase catalysis. The diiron site carries three to four carbon monoxide (CO) and two cyanide (CN-) ligands that give rise to intense infrared (IR) absorption bands. These bands are sensitive reporters of the electron density across the H-cluster, which can be addressed by infrared spectroscopy to follow redox and protonation changes at the cofactor. Synthetic variation of the metal-bridging dithiolate ligand at the diiron site, as well as site-directed mutagenesis of amino acids, provides access to the proton pathways toward the cofactor. Quantum chemical calculations are employed to specifically assign IR bands to vibrational modes of the diatomic ligands and yield refined H-cluster geometries. Here, we provide an overview of recent research on [FeFe]-hydrogenases with emphasis on experimental and computational IR studies. We describe advances in attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR) and protein film electrochemistry, as well as density functional theory (DFT) calculations. Key cofactor species are discussed in terms of molecular geometry, redox state, and protonation. Isotope editing is introduced as a tool to evaluate the cofactor geometry beyond the limits of protein crystallography. In particular, the role of proton-coupled electron transfer (PCET) in the generation of catalytically relevant redox species is addressed. We propose that site-selective protonation of the H-cluster biases surplus electrons either to the [4Fe-4S] cluster or to the diiron site. Protonation of the [4Fe-4S] cluster prevents premature reduction at the diiron site and stabilizes a reactive, terminal hydride. The observed H-cluster species are assigned to rapid H2 conversion or to reactions possibly involved in activity regulation and cellular H2 sensing. In the catalytic cycle of [FeFe]-hydrogenases, an H-cluster geometry is preserved that features a bridging CO ligand. PCET levels the redox potential for two steps of sequential cofactor reduction. The concept of consecutive PCET at a geometrically inert cofactor with tight control of electron and proton localization may inspire the design of a novel generation of biomimetic catalysts for the production of H2 as a fuel.
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Affiliation(s)
- Michael Haumann
- Department of Physics, Biophysics of Metalloenzymes, Freie Universität Berlin, 14195 Berlin, Germany
| | - Sven T. Stripp
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, 14195 Berlin, Germany
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15
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Kertess L, Wittkamp F, Sommer C, Esselborn J, Rüdiger O, Reijerse EJ, Hofmann E, Lubitz W, Winkler M, Happe T, Apfel UP. Chalcogenide substitution in the [2Fe] cluster of [FeFe]-hydrogenases conserves high enzymatic activity. Dalton Trans 2018; 46:16947-16958. [PMID: 29177350 DOI: 10.1039/c7dt03785f] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
[FeFe]-Hydrogenases efficiently catalyze the uptake and evolution of H2 due to the presence of an inorganic [6Fe-6S]-cofactor (H-cluster). This cofactor is comprised of a [4Fe-4S] cluster coupled to a unique [2Fe] cluster where the catalytic turnover of H2/H+ takes place. We herein report on the synthesis of a selenium substituted [2Fe] cluster [Fe2{μ(SeCH2)2NH}(CO)4(CN)2]2- (ADSe) and its successful in vitro integration into the native protein scaffold of [FeFe]-hydrogenases HydA1 from Chlamydomonas reinhardtii and CpI from Clostridium pasteurianum yielding fully active enzymes (HydA1-ADSe and CpI-ADSe). FT-IR spectroscopy and X-ray structure analysis confirmed the presence of structurally intact ADSe at the active site. Electrochemical assays reveal that the selenium containing enzymes are more biased towards hydrogen production than their native counterparts. In contrast to previous chalcogenide exchange studies, the S to Se exchange herein is not based on a simple reconstitution approach using ionic cluster constituents but on the in vitro maturation with a pre-synthesized selenium-containing [2Fe] mimic. The combination of biological and chemical methods allowed for the creation of a novel [FeFe]-hydrogenase with a [2Fe2Se]-active site which confers individual catalytic features.
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Affiliation(s)
- L Kertess
- Ruhr-Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstraße 150, 44801 Bochum, Germany.
| | - F Wittkamp
- Ruhr-Universität Bochum, Anorganische Chemie I/Bioanorganische Chemie, Universitätsstraße 150, 44801 Bochum, Germany.
| | - C Sommer
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - J Esselborn
- Ruhr-Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstraße 150, 44801 Bochum, Germany.
| | - O Rüdiger
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - E J Reijerse
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - E Hofmann
- Ruhr-Universität Bochum, Lehrstuhl für Biophysik, AG Röntgenstrukturanalyse an Proteinen, Universitätsstraße 150, 44801 Bochum, Germany
| | - W Lubitz
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - M Winkler
- Ruhr-Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstraße 150, 44801 Bochum, Germany.
| | - T Happe
- Ruhr-Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstraße 150, 44801 Bochum, Germany.
| | - U-P Apfel
- Ruhr-Universität Bochum, Anorganische Chemie I/Bioanorganische Chemie, Universitätsstraße 150, 44801 Bochum, Germany.
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16
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Ratzloff MW, Artz JH, Mulder DW, Collins RT, Furtak TE, King PW. CO-Bridged H-Cluster Intermediates in the Catalytic Mechanism of [FeFe]-Hydrogenase CaI. J Am Chem Soc 2018; 140:7623-7628. [PMID: 29792026 DOI: 10.1021/jacs.8b03072] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The [FeFe]-hydrogenases ([FeFe] H2ases) catalyze reversible H2 activation at the H-cluster, which is composed of a [4Fe-4S]H subsite linked by a cysteine thiolate to a bridged, organometallic [2Fe-2S] ([2Fe]H) subsite. Profoundly different geometric models of the H-cluster redox states that orchestrate the electron/proton transfer steps of H2 bond activation have been proposed. We have examined this question in the [FeFe] H2ase I from Clostridium acetobutylicum (CaI) by Fourier-transform infrared (FTIR) spectroscopy with temperature annealing and H/D isotope exchange to identify the relevant redox states and define catalytic transitions. One-electron reduction of Hox led to formation of HredH+ ([4Fe-4S]H2+-FeI-FeI) and Hred' ([4Fe-4S]H1+-FeII-FeI), with both states characterized by low frequency μ-CO IR modes consistent with a fully bridged [2Fe]H. Similar μ-CO IR modes were also identified for HredH+ of the [FeFe] H2ase from Chlamydomonas reinhardtii (CrHydA1). The CaI proton-transfer variant C298S showed enrichment of an H/D isotope-sensitive μ-CO mode, a component of the hydride bound H-cluster IR signal, Hhyd. Equilibrating CaI with increasing amounts of NaDT, and probed at cryogenic temperatures, showed HredH+ was converted to Hhyd. Over an increasing temperature range from 10 to 260 K catalytic turnover led to loss of Hhyd and appearance of Hox, consistent with enzymatic turnover and H2 formation. The results show for CaI that the μ-CO of [2Fe]H remains bridging for all of the "Hred" states and that HredH+ is on pathway to Hhyd and H2 evolution in the catalytic mechanism. These results provide a blueprint for designing small molecule catalytic analogs.
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Affiliation(s)
- Michael W Ratzloff
- Biosciences Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - Jacob H Artz
- Biosciences Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - David W Mulder
- Biosciences Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - Reuben T Collins
- Physics Department , Colorado School of Mines , Golden , Colorado 80401 , United States
| | - Thomas E Furtak
- Physics Department , Colorado School of Mines , Golden , Colorado 80401 , United States
| | - Paul W King
- Biosciences Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
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17
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Senger M, Mebs S, Duan J, Shulenina O, Laun K, Kertess L, Wittkamp F, Apfel UP, Happe T, Winkler M, Haumann M, Stripp ST. Protonation/reduction dynamics at the [4Fe-4S] cluster of the hydrogen-forming cofactor in [FeFe]-hydrogenases. Phys Chem Chem Phys 2018; 20:3128-3140. [PMID: 28884175 DOI: 10.1039/c7cp04757f] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The [FeFe]-hydrogenases of bacteria and algae are the most efficient hydrogen conversion catalysts in nature. Their active-site cofactor (H-cluster) comprises a [4Fe-4S] cluster linked to a unique diiron site that binds three carbon monoxide (CO) and two cyanide (CN-) ligands. Understanding microbial hydrogen conversion requires elucidation of the interplay of proton and electron transfer events at the H-cluster. We performed real-time spectroscopy on [FeFe]-hydrogenase protein films under controlled variation of atmospheric gas composition, sample pH, and reductant concentration. Attenuated total reflection Fourier-transform infrared spectroscopy was used to monitor shifts of the CO/CN- vibrational bands in response to redox and protonation changes. Three different [FeFe]-hydrogenases and several protein and cofactor variants were compared, including element and isotopic exchange studies. A protonated equivalent (HoxH) of the oxidized state (Hox) was found, which preferentially accumulated at acidic pH and under reducing conditions. We show that the one-electron reduced state Hred' represents an intrinsically protonated species. Interestingly, the formation of HoxH and Hred' was independent of the established proton pathway to the diiron site. Quantum chemical calculations of the respective CO/CN- infrared band patterns favored a cysteine ligand of the [4Fe-4S] cluster as the protonation site in HoxH and Hred'. We propose that proton-coupled electron transfer facilitates reduction of the [4Fe-4S] cluster and prevents premature formation of a hydride at the catalytic diiron site. Our findings imply that protonation events both at the [4Fe-4S] cluster and at the diiron site of the H-cluster are important in the hydrogen conversion reaction of [FeFe]-hydrogenases.
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Affiliation(s)
- Moritz Senger
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany.
| | - Stefan Mebs
- Department of Physics, Biophysics of Metalloenzymes, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Jifu Duan
- Faculty of Biology and Biotechnology, Photobiotechnology, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Olga Shulenina
- Faculty of Physics, St. Petersburg State University, 198504 St. Petersburg, Russian Federation
| | - Konstantin Laun
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany.
| | - Leonie Kertess
- Faculty of Biology and Biotechnology, Photobiotechnology, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Florian Wittkamp
- Faculty of Chemistry and Biochemistry, Inorganic Chemistry I, Ruhr-Universität Bochum, 44801 Bochum, Germany
| | - Ulf-Peter Apfel
- Faculty of Chemistry and Biochemistry, Inorganic Chemistry I, Ruhr-Universität Bochum, 44801 Bochum, Germany
| | - Thomas Happe
- Faculty of Biology and Biotechnology, Photobiotechnology, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Martin Winkler
- Faculty of Biology and Biotechnology, Photobiotechnology, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Michael Haumann
- Department of Physics, Biophysics of Metalloenzymes, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Sven T Stripp
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany.
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18
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Wittkamp F, Senger M, Stripp ST, Apfel UP. [FeFe]-Hydrogenases: recent developments and future perspectives. Chem Commun (Camb) 2018; 54:5934-5942. [DOI: 10.1039/c8cc01275j] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
[FeFe]-Hydrogenases are the most efficient enzymes for catalytic hydrogen turnover.
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Affiliation(s)
- F. Wittkamp
- Faculty of Chemistry and Biochemistry
- Ruhr-Universität Bochum
- 44801 Bochum
- Germany
| | - M. Senger
- Department of Physics
- Freie Universität Berlin
- 1495 Berlin
- Germany
| | - S. T. Stripp
- Department of Physics
- Freie Universität Berlin
- 1495 Berlin
- Germany
| | - U.-P. Apfel
- Faculty of Chemistry and Biochemistry
- Ruhr-Universität Bochum
- 44801 Bochum
- Germany
- Fraunhofer UMSICHT
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19
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Yuki M, Sakata K, Nakajima K, Kikuchi S, Sekine S, Kawai H, Nishibayashi Y. Dicationic Thiolate-Bridged Diruthenium Complexes for Catalytic Oxidation of Molecular Dihydrogen. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00764] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Masahiro Yuki
- Department
of Systems Innovation, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Ken Sakata
- Faculty
of Pharmaceutical Sciences, Hoshi University, Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Kazunari Nakajima
- Department
of Systems Innovation, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Syoma Kikuchi
- Faculty
of Pharmaceutical Sciences, Hoshi University, Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Shinobu Sekine
- Fuel Cell System Engineering & Development Division, Toyota Motor Corporation, Mishuku, Susono, Shizuoka 410-1193, Japan
| | - Hiroyuki Kawai
- Fuel Cell System Engineering & Development Division, Toyota Motor Corporation, Mishuku, Susono, Shizuoka 410-1193, Japan
| | - Yoshiaki Nishibayashi
- Department
of Systems Innovation, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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20
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Li RX, Liu XF, Liu T, Yin YB, Zhou Y, Mei SK, Yan J. Electrocatalytic properties of [FeFe]-hydrogenases models and visible-light-driven hydrogen evolution efficiency promotion with porphyrin functionalized graphene nanocomposite. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.03.216] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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