Infrared Spectroscopy During Electrocatalytic Turnover Reveals the Ni-L Active Site State During H2 Oxidation by a NiFe Hydrogenase.
A novel in situ IR spectroscopic approach is demonstrated for the characterization of hydrogenase during catalytic turnover. E. coli hydrogenase 1 (Hyd-1) is adsorbed on a high surface-area carbon electrode and subjected to the same electrochemical control and efficient supply of substrate as in protein film electrochemistry during spectral acquisition. The spectra reveal that the active site state known as Ni-L, observed in other NiFe hydrogenases only under illumination or at cryogenic temperatures, can be generated reversibly in the dark at ambient temperature under both turnover and non-turnover conditions. The observation that Ni-L is present at all potentials during turnover under H2 suggests that the final steps in the catalytic cycle of H2 oxidation by Hyd-1 involve sequential proton and electron transfer via Ni-L. A broadly applicable IR spectroscopic technique is presented for addressing electrode-adsorbed redox enzymes under fast catalytic turnover.
Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR (UK).
Ricardo
R
Hidalgo
Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR (UK).
Philip A
PA
Ash
Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR (UK).
Adam J
AJ
Healy
Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR (UK). kylie.vincent@chem.ox.ac.uk.
Kylie A
KA
Vincent
D055162:Biocatalysis; D020134:Catalytic Domain; D055664:Electrochemical Techniques; D004566:Electrodes; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D006859:Hydrogen / Q000737:chemistry* / Q000378:metabolism; D006864:Hydrogenase / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D009532:Nickel / Q000737:chemistry*; D010084:Oxidation-Reduction; D011522:Protons; D013055:Spectrophotometry, Infrared
D029968:Escherichia coli Proteins; D008024:Ligands; D011522:Protons; D009532:Nickel; D006859:Hydrogen; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; C000602631:hydrogenase 1, E coli
IR spectroscopy; biocatalysis; electrochemistry; hydrogenase; in situ spectroscopy