FIGURE 5.

MshB active site. A, overlay of the six MshB monomers. The locations of the active site side chains (His-13, Asp-15, Asp-16, His-144, Asp-146, and His-147) do not vary significantly, whereas the location of the Tyr-142 side chain (rainbow-colored) varies in the structures. A model of the Zn²⁺-MshB active site with Tyr-142 rotated into a catalytic location is represented by the gray wire. B, potential Tyr rotamers. The six Tyr rotamers (1–6) from the Dunbrack library are displayed as wires. The six rotamers fall into three general locations with two orientations of the phenyl ring at each location. The location of the purple side chain in A is represented by the gray stick. C, Zn²⁺-MshB active site with Tyr-142 rotated into a catalytic location (position of rotamer 5).