Fig. 2.

Amino acid binding pocket in AlaRS₄₅₃. (A) Stereoviews of simulated annealed omit F_o – F_c electron density maps for bound Ala (Top, resolution 2.08 Å, contour level 2.4 σ), Gly (Middle, 2.23 Å, 2.1 σ), and Ser (Bottom, 2.48 Å, 1.6 σ) superposed on the refined models. The amino acid and other atoms within a sphere of 3.2 Å were omitted from the model during map calculation. The protein is shown as a ribbon with orientation and colors as in Fig. 1. The bound ligands are shown in stick representation. (B) The active site of AlaRS₄₅₃ in complex with Ala (Top), Gly (Middle), and Ser (Bottom) from the respective crystal structures. Interactions with protein side chains are shown.