Electron density at the active site.

<p>Calculated <b>e</b>lectron density (2F₀-F_C map, 1σ contour level) of SU-5b <b>A</b>) with all copper and dioxygen atoms included in all 24 subunits of the molecular replacement model, <b>B</b>) with all copper and dioxygen atoms omitted in the molecular replacement model. The molecular replacement model included all side chains, but for reason of clarity only the six histidines coordinating the active site are shown. Color coding: backbone atoms = green, carbon = grey, nitrogen = blue, copper = orange, oxygen = red.