Figure 3.

A) Domain III is shown with the active site. The five parallel β‐strands are in orange. The active site residues are shown as stick representations, and the Fe and liganded water molecules are shown as spheres. B) Stereoview of the cryo‐EM map around the active site with the modeled Fe, ligands, and a single water molecule. C) Stereoview of the residues in the active site including the essential His 519 and N547. D) Stereoview of the Fe site modeled from the purple orientations (found from the structures determined) and the relaxed orientations of the ligands after minimization by DFT. The significant rearrangement of the tyrosine suggests the strain in the active site.