Fig. 1.
CcO structure and function. The two key subunits, I (pink) and II (yellow), are depicted in the membrane together with the four redox-active centers, CuA, heme a, heme a3, and CuB. In this work, the reaction is initiated by photoinduced electron injection from ruthenium bispyridyl (RubiPy). The electron transfer path is indicated in red. Proton transfer from the N-side of the membrane takes place via two pathways, D and K (blue arrows; see text). The pumped proton is released to the P-side from an as-yet-unidentified pump site above heme a3. The figure was made with the help of the crystal structure with Protein Data Bank ID code 1v54 (37) and the program VMD (45).