title: Chaetomium thermophilum formate dehydrogenase has high activity in the reduction of hydrogen carbonate (HCO3 -) to formate.
abstract: While formate dehydrogenases (FDHs) have been used for cofactor recycling in chemoenzymatic synthesis, the ability of FDH to reduce CO2could also be utilized in the conversion of CO2to useful products via formate (HCOO-). In this study, we investigated the reduction of CO2in the form of hydrogen carbonate (HCO3-) to formate by FDHs from Candida methylica (CmFDH) and Chaetomium thermophilum (CtFDH) in a NADH-dependent reaction. The catalytic performance with HCO3-as a substrate was evaluated by measuring the kinetic rates and conducting productivity assays. CtFDH showed a higher efficiency in converting HCO3-to formate than CmFDH, whereas CmFDH was better in the oxidation of formate. The pH optimum of the reduction was at pH 7-8. However, the high concentrations of HCO3-reduced the reaction rate. CtFDH was modeled in the presence of HCO3-showing that it fits to the active site. The active site setting for hydride transfer in CO2reduction was modeled. The hydride donated by NADH would form a favorable contact to the carbon atom of HCO3-, resulting in a surplus of electrons within the molecule. This would cause the complex formed by hydrogen carbonate and the hydride to break into formate and hydroxide ions.
authors.affiliation: Department of Chemistry, Gebze Technical University, Gebze 41400, Kocaeli, Turkey.
authors.forename: Aşkın Sevinç
authors.initials: AS
authors.lastname: Aslan
authors.affiliation: BioMediTech, University of Tampere, Finland.
authors.forename: Jarkko
authors.initials: J
authors.lastname: Valjakka
authors.affiliation: BioMediTech, University of Tampere, Finland.
authors.forename: Jouni
authors.initials: J
authors.lastname: Ruupunen
authors.affiliation: Vocational School of Ceyhan, University of Cukurova, Adana, Turkey.
authors.forename: Deniz
authors.initials: D
authors.lastname: Yildirim
authors.affiliation: School of Chemistry, University of Manchester, Manchester Institute of Biotechnology, 131 Princess Street, Manchester M1 7DN, UK.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Turner
authors.affiliation: Department of Biotechnology and Chemical Technology, School of Chemical Technology, Aalto University, FI-00076 Aalto, Finland Ossi.Turunen@aalto.fi.
authors.forename: Ossi
authors.initials: O
authors.lastname: Turunen
authors.affiliation: Department of Bioengineering, Gebze Technical University, Gebze 41400, Kocaeli, Turkey Ossi.Turunen@aalto.fi.
authors.forename: Barış
authors.initials: B
authors.lastname: Binay
mesh_terms: D001639:Bicarbonates / Q000378:metabolism*; D001711:Biotransformation; D020134:Catalytic Domain; D002597:Chaetomium / Q000201:enzymology*; D005560:Formate Dehydrogenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005561:Formates / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D010084:Oxidation-Reduction; D015202:Protein Engineering; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D001639:Bicarbonates; D005561:Formates; D011994:Recombinant Proteins; C030544:formic acid; D005560:Formate Dehydrogenases
keywords: NAD+-dependent formate dehydrogenase; biotransformation of CO2
  ; catalytic mechanism; kinetic parameters with hydrogen carbonate; molecular modeling