Figure 3.

PEP-binding site of Sa_enolase. Ribbon diagrams of the dimeric structure (a) and the octameric structure (b) of the PEP-bound form of Sa_enolase. The two alternative conformations of catalytic loop 1 are highlighted in red for the closed form and yellow for the open form. PEP is shown as sticks. (c) Stereoview of the F _o − F _c difference electron-density map for PEP contoured at 2.5σ. The map was calculated with coefficients for a model in which the PEP was omitted. (d) Stereoview of the PEP- and Mg²⁺-binding sites. Active-site residues and PEP are depicted as sticks with C atoms coloured blue and green, respectively. Hydrogen bonds and metal-coordination bonds are shown as black dashed lines.