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Figure 5
Tyrosine-activation and substrate-binding mechanism of RpNiR. The conformation of Tyr323 is changed by activation with NO by the removal of a water to make hydrogen bonds to a water (W3; hydrogen-bonded to Asp320) and the main-chain N atom of Gly105 (I to II). A substrate (NO2−) binds to the centre with the removal of a water (II to III). NO binds to the centre of the tyrosine-activated state (II) (II to IV). The formation of the substrate-binding state (III) and the NO-binding state (IV) is reversible. The N atoms of His99, His134 and His289, which are coordinated to T2Cu, are labelled 99N, N134 and N289, respectively.

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