Figure 5.

Coupling electron and proton transfer via the electron-transfer bridge and proton trigger loop. (a) Structure of AcNiR ds11 from serial data collection showing the electron-transfer bridge (wheat), the proton trigger loop (cyan) and the water chain W1–W10 connecting the T1Cu and T2Cu sites to bulk solvent. Some partial-occupancy waters have been omitted for clarity. (b) Superposition of the electron-transfer bridge and proton trigger loop residues, showing multiple conformations of Met141 and the Glu139 side chains from serial data sets ds1 (green), ds11 (orange), ds17 (purple) and ds30 (cyan).