title: Enhanced oxygen-tolerance of the full heterotrimeric membrane-bound [NiFe]-hydrogenase of Ralstonia eutropha.
abstract: Hydrogenases are oxygen-sensitive enzymes that catalyze the conversion between protons and hydrogen. Water-soluble subcomplexes of membrane-bound [NiFe]-hydrogenases (MBH) have been extensively studied for applications in hydrogen-oxygen fuel cells as they are relatively tolerant to oxygen, although even these catalysts are still inactivated in oxidative conditions. Here, the full heterotrimeric MBH of Ralstonia eutropha, including the membrane-integral cytochrome b subunit, was investigated electrochemically using electrodes modified with planar tethered bilayer lipid membranes (tBLM). Cyclic voltammetry and chronoamperometry experiments show that MBH, in equilibrium with the quinone pool in the tBLM, does not anaerobically inactivate under oxidative redox conditions. In aerobic environments, the MBH is reversibly inactivated by O2, but reactivation was found to be fast even under oxidative redox conditions. This enhanced resistance to inactivation is ascribed to the oligomeric state of MBH in the lipid membrane.
authors.affiliation: School of Biomedical Sciences, the Astbury Centre for Structural Molecular Biology, and School of Physics & Astronomy, University of Leeds , Leeds LS2 9JT, United Kingdom.
authors.forename: Valentin
authors.initials: V
authors.lastname: Radu
authors.forename: Stefan
authors.initials: S
authors.lastname: Frielingsdorf
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Evans
authors.forename: Oliver
authors.initials: O
authors.lastname: Lenz
authors.forename: Lars J C
authors.initials: LJ
authors.lastname: Jeuken
mesh_terms: D020118:Cupriavidus necator / Q000201:enzymology*; D004566:Electrodes; D006864:Hydrogenase / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism*
chemical_list: D008051:Lipid Bilayers; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; D010100:Oxygen