Figure 2.

Ca²⁺ and heme iron coordination. A, The distal Ca²⁺ coordinated by the side chains of Asp-43, Asp-50, and Ser-52, backbone carbonyls of Val-46, Gly-48, and Asp-43, and a water molecule. B, The proximal Ca²⁺ coordinated by the side chains of Thr-168, Asp-211, Thr-214, and Asp-219 and the backbone carbonyls of Thr-168, Thr-214, and Thr-217. C, The active site showing the catalytic His-42, ligand-binding Arg-38, heme and the fifth heme iron ligand His-167, and the P-X-P-X motif of PviPRX9 (137PPPQ140). Images were rendered with Chimera version 1.11.