Cytochrome c oxidase (CcO) is a redox-driven proton pump that powers aerobic respiratory chains. We show here by multi-scale molecular simulations that a protonated water cluster near the active site is likely to serve as the transient proton-loading site (PLS) that stores a proton during the pumping process. The pKa of this water cluster is sensitive to the redox states of the enzyme, showing distinct similarities to other energy converting proton pumps.
Keywords: bioenergetics; electron transfer; enzymes; molecular dynamics; proton transfer.
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