The proton pumping pathway of bovine heart cytochrome c oxidase
Open Access
- 6 March 2007
- journal article
- research 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. 104 (10), 4200-4205
- https://doi.org/10.1073/pnas.0611627104
Abstract
X-ray structures of bovine heart cytochrome c oxidase have suggested that the enzyme, which reduces O2 in a process coupled with a proton pumping process, contains a proton pumping pathway (H-pathway) composed of a hydrogen bond network and a water channel located in tandem across the enzyme. The hydrogen bond network includes the peptide bond between Tyr-440 and Ser-441, which could facilitate unidirectional proton transfer. Replacement of a possible proton-ejecting aspartate (Asp-51) at one end of the H-pathway with asparagine, using a stable bovine gene expression system, abolishes the proton pumping activity without influencing the O2 reduction function. Blockage of either the water channel by a double mutation (Val386Leu and Met390Trp) or proton transfer through the peptide by a Ser441Pro mutation was found to abolish the proton pumping activity without impairment of the O2 reduction activity. These results significantly strengthen the proposal that H-pathway is involved in proton pumping.Keywords
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