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Figure 1
Details of the T2Cu sites of RpNiR and its D97N mutant. (a) RpNiR D97N–NO, (b) wt RpNiR–NO and (c) wt RpNiR without NO treatment in the same space group I213. In both NO-bound structures Tyr323 is rotated away from the T2Cu site compared with the wild-type structure, where it hydrogen-bonds to an aspartic acid residue. W3 is not visible in the wild type here owing to limited resolution, but is well defined in high-resolution structures. (d) RpNiR–NO2− shows nitrite bound to T2Cu in an outward-facing manner. In (a) to (d) 2Fo − Fc electron-density maps are shown at 1.0σ (blue mesh) and the Fo − Fc OMIT maps of NO2− and NO are at 7σ (red mesh). His240 has been omitted for clarity. (e) An Fo − Fc OMIT anomalous map is shown at the 15σ level around copper (1.33 Å X-ray wavelength; red mesh) and at the 20σ level around iron (1.7 Å X-ray wavelength; orange mesh). Hydrogen bonds and copper-coordination bonds are shown as dashed black and red lines, respectively. The two adjacent monomers that form the catalytic centre are coloured magenta and cyan, respectively.

IUCrJ
Volume 5| Part 4| July 2018| Pages 510-518
ISSN: 2052-2525
https://doi.org/10.1107/S2052252518008242