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Figure 1
Comparison of T1Cu and T2Cu sites and the interface of the cyt c domain in wtRpNiR, as-isolated, oxidized and reduced. (A) T1Cu site of oxidized RpNiR (3ziy) shows an ideal tetrahedral geometry. (B) In contrast, in the reduced enzyme, Met148 adopts two conformations, with T1Cu to Sδ distances of 2.67 and 4.4 Å. (C) T2Cu site of as-isolated wtRpNiR (3ziy). (D) T2Cu site of reduced wtRpNiR with Cu bound to a single water, W1. Loss of W2 likely weakens the anchoring of the gatekeeper residue Tyr323. (E) Conformation of residues involved in electron transfer at the interface between the cyt c domain and the core domain in as-isolated wtRpNiR (3ziy). (F) The inter-domain interface in reduced wtRpNiR reveals the flexibility of Gly362 and Thr363, present in two conformations. The residues from neighbouring molecules are coloured green and blue. The 2Fo − Fc electron-density map is shown as a grey mesh at the 1σ level. The red spheres represent the water molecules and the deep blue spheres the Cu ions. Important hydrogen bonds are shown as black dashed lines; yellow dotted lines represent through-bonded interactions and red dashed lines are metal coordinating bonds.

IUCrJ
Volume 13| Part 4| July 2026|
ISSN: 2052-2525
https://doi.org/10.1107/S2052252526004549