Interconversions of P and F intermediates of cytochrome c oxidase from Paracoccus denitrificans

Iris von der Hocht, Jessica H. van Wonderen, Florian Hilbers, Heike Angerer, Fraser MacMillan, Hartmut Michel

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20 Citations (Scopus)


Cytochrome c oxidase (CcO) is the terminal enzyme of the respiratory chain. This redox-driven proton pump catalyzes the four-electron reduction of molecular oxygen to water, one of the most fundamental processes in biology. Elucidation of the intermediate structures in the catalytic cycle is crucial for understanding both the mechanism of oxygen reduction and its coupling to proton pumping. Using CcO from Paracoccus denitrificans, we demonstrate that the artificial F state, classically generated by reaction with an excess of hydrogen peroxide, can be converted into a new P state (in contradiction to the conventional direction of the catalytic cycle) by addition of ammonia at pH 9. We suggest that ammonia coordinates directly to CuB in the binuclear active center in this P state and discuss the chemical structures of both oxoferryl intermediates F and P. Our results are compatible with a superoxide bound to CuB in the F state.
Original languageEnglish
Pages (from-to)3964-3969
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America (PNAS)
Issue number10
Publication statusPublished - 22 Feb 2011

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