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![[Figure 3]](xh5063fig3mag.jpg)
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Figure 3
(a) Reconstructed catalytic cycle of LsAA9A with Cell3 as substrate and H2O2 as co-substrate. The Cl−-bound structure represents an unreactive mimic of the H2O2-bound state (* means Cl−). The label H2O2 is shown in parentheses to indicate that hydrogen peroxide was not added experimentally. Cu(II)_H2O2_substrate intermediates are likely to be too reactive to be captured by single-crystal crystallography. A product-bound structure is included but has not yet been trapped crystallographically. See the main text for further details. (b) Schematic representation of the active-site geometries of LsAA9A under four different conditions, Cu(II), Cu(I), Cu(I)–Cell3 and Cu(II)–Cell3, showing the mean distances of atoms coordinated to the copper center. The figure illustrates selected significant structural parameter differences according to the Tukey–Kramer test, highlighted in yellow. Only differences between states that can be considered to be sequential according to the scheme in (a) are highlighted: LsAA9A_Cu(II)_LD → LsAA9A_Cu(I)_LD → LsAA9A_Cu(I)_Cell3_LD → LsAA9A_Cu(II)_Cell3_LD [mimicking LsAA9A_Cu(II)_Cell3-HO—OH] →→ LsAA9A_Cu(I)_LD. From LsAA9A_Cu(I)_LD to LsAA9A_Cu(I)_Cell3_LD, θ3 changes significantly, decreasing from 168.27 ± 0.61° to 161.37 ± 1.89. The transition from LsAA9A_Cu(I)_Cell3_LD to LsAA9A_Cu(II)_Cell3_LD involves marked changes in θ2, θ3 and the Cu–His1 Nδ1 and Cu–Tyr Oη distances: θ2 decreases from 100.56 ± 1.10° to 90.75 ± 2.03°, θ3 increases from 161.37 ± 1.89° to 166.90 ± 2.12°, the Cu–His1 Nδ1 distance increases from 1.95 ± 0.03 Å to 2.11 ± 0.08 Å and the Cu–Tyr Oη distance decreases from 2.72 ± 0.06 Å to 2.56 ± 0.04 Å. Finally, the transition from LsAA9A_Cu(II)_Cell3_LD to LsAA9A_Cu(I)_LD involves marked changes in θ2, θT and the Cu–Tyr Oη distance: θ2 increases from 90.75 ± 2.03° to 97.92 ± 1.60°, θT decreases from 12.40 ± 2.07° to 4.90 ± 2.06° and the Cu–Tyr Oη distance increases from 2.56 ± 0.04 Å to 2.84 ± 0.08 Å. A similar illustration, highlighting significant differences according to pairwise t-tests, is shown in Supplementary Fig. S2. (c) Definition of θ1, θ2, θ3 and θT. θ1–θ3 are the N—Cu—N bond angles as indicated. θT is the angle between the Nδ1–Cu–NAm plane and the Nɛ2–Cu vector. |
![[Figure 3]](xh5063fig3.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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