How oxygen reacts with oxygen-tolerant respiratory [NiFe]-hydrogenases.
An oxygen-tolerant respiratory [NiFe]-hydrogenase is proven to be a four-electron hydrogen/oxygen oxidoreductase, catalyzing the reaction 2 H2 + O2 = 2 H2O, equivalent to hydrogen combustion, over a sustained period without inactivating. At least 86% of the H2O produced by Escherichia coli hydrogenase-1 exposed to a mixture of 90% H2 and 10% O2 is accounted for by a direct four-electron pathway, whereas up to 14% arises from slower side reactions proceeding via superoxide and hydrogen peroxide. The direct pathway is assigned to O2 reduction at the [NiFe] active site, whereas the side reactions are an unavoidable consequence of the presence of low-potential relay centers that release electrons derived from H2 oxidation. The oxidase activity is too slow to be useful in removing O2 from the bacterial periplasm; instead, the four-electron reduction of molecular oxygen to harmless water ensures that the active site survives to catalyze sustained hydrogen oxidation.
Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, Oxford OX1 3QR, United Kingdom.
Philip
P
Wulff
Christopher C
CC
Day
Frank
F
Sargent
Fraser A
FA
Armstrong
D020134:Catalytic Domain; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D006864:Hydrogenase / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D020836:Protein Structure, Quaternary
D029968:Escherichia coli Proteins; D009532:Nickel; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; C043296:nickel-iron hydrogenase; C029746:uptake hydrogenase; D006864:Hydrogenase; D010100:Oxygen
Fe-S cluster; hydrogen; mass spectrometry