The active sites of H. volcanii MSH. a) High-occupancy glyoxylate complex rendered in stick form with carbon atoms yellow, oxygen red, and nitrogen blue. The magnesium ion and coordinating water molecules are shown as spheres in purple and red respectively. Distances are shown in angstroms with hydrogen bonds yellow and metal-ligand bonds in black. The side chain of Val 191 has been removed for clarity. b) Pyruvate/Acetyl-CoA ternary complex rendered as in part a, but with carbon atoms in green and sulfur in tan. Additionally, close contacts are indicated with red dashed lines. Side chains for Glu 190 and Val 191 have been omitted for clarity.