
Representative magnesium-binding sites. An Fo–Fc omit electron density map is illustrated as mesh contoured at 3σ. Note the evident octahedral geometry of the coordination shell. Mg2+ and water are shown as green and red spheres, respectively. (A) Mg2+ is coordinated at OP1 of G19 and five water molecules. (B) Mg2+ is coordinated to the N7 of G15 and five water molecules.










