Fig. 4.

The 3^rd Mg²⁺ ion in hPol η catalysis. A stereo view of the three metal ions observed in the intermediate state of 230s after Mg²⁺ addition, which consists of a mixture of PS (blue) and RS (yellow). The 3^rd Mg²⁺ has six ligands, four of which are water molecules. The 2Fo-Fc map contoured at 1.5 σ (grey) and Fo-Fc map with the 3^rd Mg²⁺ omitted contoured at 4.0 σ (green) are overlaid with the ball-and-stick model.