Figure 2.

Ribbon diagram of BeF⋅PSP (A) and stereoview of the active site (B). Ball-and-stick representations of the sidechain carbon, nitrogen, and oxygen atoms are colored green, blue, and red, respectively. In A, the sidechains of highly conserved active site residues, Asp-11, Ser-99, Lys-144, Asp-167, and Asp-171, are shown in ball-and-stick form. BeF (red balls and orange bonds) is bonded to Asp-11 Oδ in the center of the active site (33). In B, the 2F_o − F_c electron density map covering the magnesium (cyan) and fluorine (red) atoms was calculated in the absence of these atoms and is shown contoured at 1σ. The dashed lines represent hydrogen bonds, salt bridges, and metal–ligand interactions. Three of the Mg²⁺ ligands (two water molecules and Asp-13-C = O) are not shown.