FIGURE 5

FIGURE 5

4D motif in TcAChE. The four Asp residues, D326, D389, D392, and D393, are shown as sticks, with carbons in green, oxygens in red, and nitrogens in blue. Solvent waters are shown as blue spheres, and the metal ions as magenta spheres, with their sizes proportionate to their Van der Waals radii; the oxygens of the uranyl moiety are shown as red spheres. Noncovalent hydrogen bonds and ionic bonds are shown as dashed black lines. (a) Apo TcAChE; (b) Mg⁺²/TcAChE; (c) Ca⁺²/TcAChE; and (d) UO₂⁺²/TcAChE