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

Vincent C-C Wang, Shams T A Islam, Mehmet Can, Stephen W Ragsdale, Fraser A Armstrong

Index: J. Phys. Chem. B 119 , 13690-7, (2015)

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Abstract

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.