Fig. 2.

Structure of the $\mathrm{PGM}\mathrm{\text{-}}{\mathrm{MgF}}_3\mathrm{\text{-}}\mathrm{G}6\mathrm{P}\mathrm{\text{-}}\mathrm{TSA}$ complex active site. (A) The difference Fourier map and the anomalous substructure of the $\mathrm{PGM}\mathrm{\text{-}}{\mathrm{MgF}}_3\mathrm{\text{-}}\mathrm{G}6\mathrm{P}\mathrm{\text{-}}\mathrm{TSA}$ complex. Anomalous difference density contoured at 3σ is shown as a magenta mesh. A large peak (height $7.1\sigma$) is visible for the phosphorus atom in G6P. No corresponding phosphorus peak was observed in the active site confirming the assignment of the trigonal planar species as ${\mathrm{MgF}}_3^{-}$ and not ${\mathrm{PO}}_3^{-}$. The difference electron density (${\mathrm{F}}_o-{\mathrm{F}}_c$) from the same data is shown as a gray mesh contoured at 3σ for G6P and the ${\mathrm{MgF}}_3^{-}$ moiety before their inclusion in the model. (B) Schematic view of the $\mathrm{PGM}\mathrm{\text{-}}{\mathrm{MgF}}_3\mathrm{\text{-}}\mathrm{\text{sugar phosphate}}\mathrm{\text{-}}\mathrm{TSA}$ complex active site. Three sugar moieties were studied: G6P ($\mathrm{R}=\mathrm{OH}$, $\mathrm{X}=\mathrm{O}$); 6-deoxy-6-(phosphonomethyl)-D-glucopyranoside ($\mathrm{R}=\mathrm{OH}$, $\mathrm{X}={\mathrm{CH}}_2$); 2-deoxy-G6P ($\mathrm{R}=\mathrm{H}$, $\mathrm{X}=\mathrm{O}$).