Figure 5.

The 2.25-Å resolution crystal structure of the 2–murine iNOS Δ114 complex and comparison to the murine iNOS dimer structure. Two views of the refined model of the 2–murine iNOS Δ114 complex are shown. Compound 2 (green) and heme (dark red) both are shown with blue nitrogens and red oxygens. The sulfur (yellow) of Cys-194 (magenta) coordinates the heme iron (yellow sphere). The water molecules described in the text are shown as red spheres, and in Tyr-367, Tyr-485, and Gln-257 side chains are shown in orange with red oxygens and blue nitrogens. Both iron coordination and hydrogen bonds are shown as dashed lines; other iNOS Δ114 atoms are shown in gray. Numerous residues are not shown for clarity, including residues 486–496 and the side chains of Val-346, Asn-348, and Met-349 in A and Gln-257 and surrounding residues (241–345) in B.