Figure 7.

(a) Close-up view of active site from the superposition of Mn²⁺₂-TcFIGase_ox (C = white) with Mn²⁺₂-TcFIGase (C = cyan). Metal coordination and hydrogen bond interactions in Mn²⁺₂-TcFIGase_ox are represented by red and green dashed lines, respectively. (b) Simulated annealing omit maps (purple, contoured at 3σ) of Mn²⁺ ions and Mn²⁺-bound solvent molecules observed in Mn²⁺₂-TcFIGase_ox soaked in a buffer solution containing 20 mM MnCl₂ at pH 8.5. Atoms are color-coded as follows: C = white, N = blue, O = red, Mn²⁺ = pink spheres, solvent = red spheres. Metal coordination and hydrogen bond interactions are represented by blue and green dashed lines, respectively. Note the reduced Mn²⁺_A occupancy and conformational change of former Mn²⁺_A ligand D142.