Figure 3.

Stereoview showing the active site Mg²⁺ and Na⁺ binding sites. Both are changed only very subtly by substituting for His-418 in the native structure (red) with either Asn (blue) or Glu (green). The substrate will bind initially in the lower left between positions 418 and 999. (Figure prepared with Molscript.¹⁹)