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Investigations by Protein Film Electrochemistry of Alternative Reactions of Nickel-Containing Carbon Monoxide Dehydrogenase

Wang, Vincent C.-C., Islam, Shams T. A., Can, Mehmet, Ragsdale, Stephen W., Armstrong, Fraser A.
The Journal of physical chemistry 2015 v.119 no.43 pp. 13690-13697
carbon dioxide, carbon electrodes, carbon monoxide, cyanides, electrochemistry, enzymes, formates, hydrogen, nitrous oxide, oxidation, oxygen, physical chemistry, prediction
Protein film electrochemistry has been used to investigate reactions of highly active nickel-containing carbon monoxide dehydrogenases (CODHs). When attached to a pyrolytic graphite electrode, these enzymes behave as reversible electrocatalysts, displaying CO₂ reduction or CO oxidation at minimal overpotential. The O₂ sensitivity of CODH is suppressed by adding cyanide, a reversible inhibitor of CO oxidation, or by raising the electrode potential. Reduction of N₂O, isoelectronic with CO₂, is catalyzed by CODH, but the reaction is sluggish, despite a large overpotential, and results in inactivation. Production of H₂ and formate under highly reducing conditions is consistent with calculations predicting that a nickel-hydrido species might be formed, but the very low rates suggest that such a species is not on the main catalytic pathway.