Fig. 5

Structural analysis of TtAA10A. a The overall structure of TtAA10A is shown as a cartoon coloured by secondary structure with its surrounding surface shown in grey. The histidine brace active site copper is shown as an orange sphere with its coordinating residues displayed as sticks coloured by atom type. The secondary copper site and a separate sodium ion binding site are shown with cyan and grey spheres, respectively, with coordinating residues coloured as for the histidine brace. b Close up view of the histidine brace in the enzyme active site. The 2F_obs–F_calc map for the final structure is shown contoured at 1σ as a blue mesh. c Close up view of the second copper binding site with the copper ion shown as a cyan sphere. The Strep-Tag-derived histidine which reaches over from a symmetry related molecule to interact with the copper ion is shown with white carbon atoms and is marked with an *. In both b and c, the difference anomalous map is shown contoured at 4σ as a pink mesh confirming the positions of the copper ions