Homogeneous catalytic O 2 reduction to water by a cytochrome c oxidase model with trapping of intermediates and mechanistic insights
- 23 August 2011
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 108 (34), 13990-13994
- https://doi.org/10.1073/pnas.1104698108
Abstract
An efficient and selective four-electron plus four-proton (4e(-)/4H(+)) reduction of O(2) to water by decamethylferrocene and trifluoroacetic acid can be catalyzed by a synthetic analog of the heme a(3)/Cu(B) site in cytochrome c oxidase ((6)LFeCu) or its Cu-free version ((6)LFe) in acetone. A detailed mechanistic-kinetic study on the homogeneous catalytic system reveals spectroscopically detectable intermediates and that the rate-determining step changes from the O(2)-binding process at 25 °C room temperature (RT) to the O-O bond cleavage of a newly observed Fe(III)-OOH species at lower temperature (-60 °C). At RT, the rate of O(2)-binding to (6)LFeCu is significantly faster than that for (6)LFe, whereas the rates of the O-O bond cleavage of the Fe(III)-OOH species observed (-60 °C) with either the (6)LFeCu or (6)LFe catalyst are nearly the same. Thus, the role of the Cu ion is to assist the heme and lead to faster O(2)-binding at RT. However, the proximate Cu ion has no effect on the O-O bond cleavage of the Fe(III)-OOH species at low temperature.Keywords
This publication has 29 references indexed in Scilit:
- CO and O2 Binding to Pseudo-tetradentate Ligand−Copper(I) Complexes with a Variable N-Donor Moiety: Kinetic/Thermodynamic Investigation Reveals Ligand-Induced Changes in Reaction MechanismJournal of the American Chemical Society, 2010
- Mononuclear Copper Complex-Catalyzed Four-Electron Reduction of OxygenJournal of the American Chemical Society, 2010
- Bovine cytochrome c oxidase structures enable O 2 reduction with minimization of reactive oxygens and provide a proton-pumping gateProceedings of the National Academy of Sciences of the United States of America, 2010
- Catalytic Reduction of O2 by Cytochrome c Using a Synthetic Model of Cytochrome c OxidaseJournal of the American Chemical Society, 2009
- Catalytic Activity of Biscobalt Porphyrin-Corrole Dyads Toward the Reduction of DioxygenInorganic Chemistry, 2009
- A Cytochrome c Oxidase Model Catalyzes Oxygen to Water Reduction Under Rate-Limiting Electron FluxScience, 2007
- Mechanism of Four-Electron Reduction of Dioxygen to Water by Ferrocene Derivatives in the Presence of Perchloric Acid in Benzonitrile, Catalyzed by Cofacial Dicobalt PorphyrinsJournal of the American Chemical Society, 2004
- Electrocatalytic reduction of dioxygen to water by tren-capped porphyrins, functional models of cytochrome c oxidase†Chemical Communications, 1999
- Novel Multinuclear Catalysts for the Electroreduction of Dioxygen Directly to WaterAccounts of Chemical Research, 1997
- Reaction of dioxygen with cytochrome c oxidase reduced to different degrees: indications of a transient dioxygen complex with copper-BBiochemistry, 1992