Fig. 3. T2Cu site in nitrite-bound Br2DNiR: SRX v SF-ROX structures.
(A) The 1 Å SRX structure (orange) showing two top-hat conformations of nitrite and Asp92 (proximal and gatekeeper). A partial water (WG) and movement of Leu100 oxygen atom (OP > OG) are also seen. (B) The 1.3 Å XFEL FRIC structure (magenta) showing single nitrite in side-on position and Asp92 in proximal conformation. (C) SRX T2Cu site with bidentate-bonded top-hat nitrite present. (D) Alternative T2Cu of SRX structure with “bent top-hat” conformation of nitrite. (E) SF-ROX structure with horizontal side-on coordination of nitrite. Bonding and coordination of waters and atoms are shown for all. OMIT Fo − Fc electron density maps around nitrite molecules are contoured at 5σ level and colored green. 2Fo − Fc electron density maps are contoured at 1σ level in gray. Water molecules are shown as red spheres, and T2Cu is shown as a blue sphere. Hydrogen bonds are shown as black dashed lines, and coordination distances to T2Cu are shown as red dashed lines.