@article{HartmannLeimkuehler2013,
  author    = {Hartmann, Tobias and Leimk{\"u}hler, Silke},
  title     = {The oxygen-tolerant and NAD+-dependent formate dehydrogenase from Rhodobacter capsulatus is able to catalyze the reduction of CO2 to formate},
  series = {The FEBS journal},
  volume    = {280},
  journal   = {The FEBS journal},
  number    = {23},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {1742-464X},
  doi       = {10.1111/febs.12528},
  pages     = {6083 -- 6096},
  year      = {2013},
  abstract  = {The formate dehydrogenase from Rhodobactercapsulatus (RcFDH) is an oxygen-tolerant protein with an ()(2) subunit composition that is localized in the cytoplasm. It belongs to the group of metal and NAD(+)-dependent FDHs with the coordination of a molybdenum cofactor, four [Fe4S4] clusters and one [Fe2S2] cluster associated with the -subunit, one [Fe4S4] cluster and one FMN bound to the -subunit, and one [Fe2S2] cluster bound to the -subunit. RcFDH was heterologously expressed in Escherichiacoli and characterized. Cofactor analysis showed that the bis-molybdopterin guanine dinucleotide cofactor is bound to the FdsA subunit containing a cysteine ligand at the active site. A turnover rate of 2189min(-1) with formate as substrate was determined. The back reaction for the reduction of CO2 was catalyzed with a k(cat) of 89min(-1). The preference for formate oxidation shows an energy barrier for CO2 reduction of the enzyme. Furthermore, the FMN-containing and [Fe4S4]-containing -subunit together with the [Fe2S2]-containing -subunit forms a diaphorase unit with activities for both NAD(+) reduction and NADH oxidation. In addition to the structural genes fdsG, fdsB, and fdsA, the fds operon in R.capsulatus contains the fdsC and fdsD genes. Expression studies showed that RcFDH is only active when both FdsC and FdsD are present. Both proteins are proposed to be involved in bis-molybdopterin guanine dinucleotide modification and insertion into RcFDH.},
  language  = {en}
}
@article{MitrovaTadjoungWaffoKaufmannetal.2018,
  author    = {Mitrova, Biljana and Tadjoung Waffo, Armel Franklin and Kaufmann, Paul and Iobbi-Nivol, Chantal and Leimk{\"u}hler, Silke and Wollenberger, Ulla},
  title     = {Trimethylamine N-Oxide Electrochemical Biosensor with a Chimeric Enzyme},
  series = {ChemElectroChem},
  volume    = {6},
  journal   = {ChemElectroChem},
  number    = {6},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {2196-0216},
  doi       = {10.1002/celc.201801422},
  pages     = {1732 -- 1737},
  year      = {2018},
  abstract  = {For the first time, an enzyme-based electrochemical biosensor system for determination of trimethylamine N-oxide (TMAO) is described. It employs an active chimeric variant of TorA in combination with an enzymatically deoxygenating system and a low-potential mediator for effective regeneration of the enzyme and cathodic current generation. TMAO reductase (TorA) is a molybdoenzyme found in marine and most enterobacteria that specifically catalyzes the reduction of TMAO to trimethylamine (TMA). The chimeric TorA, named TorA-FDH, corresponds to the apoform of TorA from Escherichia coli reconstituted with the molybdenum cofactor from formate dehydrogenase (FDH). Each enzyme, TorA and TorA-FDH, was immobilized on the surface of a carbon electrode and protected with a dialysis membrane. The biosensor operates at an applied potential of -0.8V [vs. Ag/AgCl (1M KCl)] under ambient air conditions thanks to an additional enzymatic O-2-scavenger system. A comparison between the two enzymatic sensors revealed a much higher sensitivity for the biosensor with immobilized TorA-FDH. This biosensor exhibits a sensitivity of 14.16nA/M TMAO in a useful measuring range of 2-110M with a detection limit of LOD=2.96nM (S/N=3), and was similar for TMAO in buffer and in spiked serum samples. With a response time of 16 +/- 2 s, the biosensor is stable over prolonged daily measurements (n=20). This electrochemical biosensor provides suitable applications in detecting TMAO levels in human serum.},
  language  = {en}
}
@article{LaunDuffusWahlefeldetal.2022,
  author    = {Laun, Konstantin and Duffus, Benjamin R. and Wahlefeld, Stefan and Katz, Sagie and Belger, Dennis Heinz and Hildebrandt, Peter and Mroginski, Maria Andrea and Leimk{\"u}hler, Silke and Zebger, Ingo},
  title     = {Infrared spectroscopy flucidates the inhibitor binding sites in a metal-dependent formate dehydrogenase},
  series = {Chemistry - a European journal},
  journal   = {Chemistry - a European journal},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0947-6539},
  doi       = {10.1002/chem.202201091},
  pages     = {8},
  year      = {2022},
  abstract  = {Biological carbon dioxide (CO2) reduction is an important step by which organisms form valuable energy-richer molecules required for further metabolic processes. The Mo-dependent formate dehydrogenase (FDH) from Rhodobacter capsulatus catalyzes reversible formate oxidation to CO2 at a bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor. To elucidate potential substrate binding sites relevant for the mechanism, we studied herein the interaction with the inhibitory molecules azide and cyanate, which are isoelectronic to CO2 and charged as formate. We employed infrared (IR) spectroscopy in combination with density functional theory (DFT) and inhibition kinetics. One distinct inhibitory molecule was found to bind to either a non-competitive or a competitive binding site in the secondary coordination sphere of the active site. Site-directed mutagenesis of key amino acid residues in the vicinity of the bis-MGD cofactor revealed changes in both non-competitive and competitive binding, whereby the inhibitor is in case of the latter interaction presumably bound between the cofactor and the adjacent Arg587.},
  language  = {en}
}
@article{LaunDuffusKumaretal.2022,
  author    = {Laun, Konstantin and Duffus, Benjamin R. and Kumar, Hemant and Oudsen, Jean-Pierre H. and Karafoulidi-Retsou, Chara and Waffo, Armel Tadjoung and Hildebrandt, Peter and Ly, Khoa Hoang and Leimk{\"u}hler, Silke and Katz, Sagie and Zebger, Ingo},
  title     = {A minimal light-driven system to study the enzymatic CO2 reduction of formate dehydrogenase},
  series = {ChemCatChem : the European Society Journal for Catalysis},
  volume    = {14},
  journal   = {ChemCatChem : the European Society Journal for Catalysis},
  number    = {24},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1867-3880},
  doi       = {10.1002/cctc.202201067},
  pages     = {7},
  year      = {2022},
  abstract  = {A minimal light-driven approach was established for studying enzymatic CO2 conversion spectroscopically. The system consists of a photosensitizer Eosin Y, EDTA as a sacrificial electron donor and substrate source, and formate dehydrogenase from Rhodobacter capsulatus (RcFDH) as a biocatalyst. This simplified three-component system provides a photo-triggered control for in situ characterization of the entire catalytic reaction. Direct reduction of RcFDH by the photosensitizer without additional electron carriers was confirmed via UV-Vis spectroscopy, while GC-MS and IR spectroscopy were used to follow photoinduced CO2 generation from EDTA and its subsequent enzymatic reduction, yielding the product formate. Photo-driven and in vitro, dye-based CO2 reduction was inhibited by azide under a mixed (competitive-non-competitive) inhibition mode. IR spectroscopy reveals displacement of the competitively-bound azide by CO2, reflecting an interaction of both with the active site cofactor. This work comprises a proof-of-concept for a new approach to employ light for regulating the reaction of formate dehydrogenases and other CO2 reductases.},
  language  = {en}
}