Figure 4.

Electron tunnelling network simulation in a haem a knockout allows an examination of direct Cu_A to catalytic cluster electron transfer, which may short circuit important proton pumping action. Using the default reorganization energy and barrier for cluster reduction of 0.7 eV, Cu_A to cluster electron tunnelling is 0.4 ms (fine dashed lines). Increasing the cluster reduction reorganization energy of 1.7 eV slows this electron tunnelling to 0.2 s (medium dashed lines). A 2.5 eV reorganization energy slows this potential short circuit to about a minute.