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![Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F55858.jpg&w=3840&q=50)
Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase
Published on: December 4, 2017
Ni-elimination from the active site of the standard [NiFe]‑hydrogenase upon oxidation by O2
Koji Nishikawa1, Satoko Mochida1, Takeshi Hiromoto1
1Department of Picobiology, University of Hyogo, 3-2-1 Koto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan.
Abstract:
Hydrogenase is a key enzyme for a coming hydrogen energy society, because it has strong catalytic activities on both uptake and production of dihydrogen. We, however, have to overcome the sensitivity against O2 of the enzyme, because hydrogenase is, generally, easily inactivated in the presence of O2. In this study, we have revisited the crystal structures of [NiFe]‑hydrogenase from sulfate-reducing bacterium in the several oxidized and reduced conditions. Our results revealed that the Ni-Fe active site of the enzyme exposed into O2 showed two forms, Form-1 and Form-2. The Ni-Fe active site in Form-1 showed the typical Ni-B (inactive ready) structure, whereas those in Form-2 lost Ni with no relation to an exposure time to O2, and two cysteinyl sulfur ligands made a disulfide bond. On the other hand, the formation of sulfenylation of the cysteinyl ligand to Ni, which is often observed in the oxidized form, did not correlate with the Ni-elimination, but with exposure time to O2.
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