A proposal for the site and mechanism of redox-linked proton translocation in cytochrome c oxidase.

In this paper, we present a detailed mechanistic model for the redox-linked proton pump of cytochrome c oxidase. Using the spectroscopic properties of CuA, we have constructed a molecular orbital model for the electronic structure of the CuA site. One prediction of this model is that a ligand rearrangement should occur upon reduction of CuA. We further describe a detailed mechanism for proton pumping which utilizes this redox-linked CuA ligand rearrangement as its central feature. The turnover cycle of this proton pump model is then discussed in terms of the theoretical thermodynamic and kinetic requirements of a redox-linked proton pump.