Fig 1.
Tyrosinase and catechol oxidase activity.
Fig 2.
A Molecular surface representation of a monomeric catechol oxidase from Aspergillus oryzae (in cyan) shows the accessibility of the binuclear copper centre to the protein surface. Copper ions are represented in orange. The central bundle of four α-helices is shown in green. B The dimeric structure of AoCO4. The dimeric counterpart is in grey. The long N-terminal α-helix of the monomer is represented in pink. The observed carbohydrates are shown as stick models.
Fig 3.
Copper sites in the crystal structures of catechol oxidase from Aspergillus oryzae.
An Fo−Fc omit map of oxygen species at the copper site is shown in green at the 3σ contour level. A 4J3P (now shown with a peroxide moiety) B met/deoxy (molecule B is shown) and C deoxy (molecule B is shown).
Fig 4.
Copper site of the met/deoxy structure of catechol oxidase from Aspergillus oryzae.
An Fo−Fc omit map of oxygen species at the copper site is shown in green at the 3σ contour level. A: molecule A, the Cu-Cu distance was 4.3 Å, and the distance between water molecules was 2.5 Å. B: molecule B, Cu-Cu distance was 4.4 Å, and the distance between water molecules was 2.6 Å, C: molecule C, the Cu-Cu distance was 4.4 Å, and the distance from atom O2 of the peroxide moiety to water was 2.5 Å. D: molecule D, the Cu-Cu distance was 4.5 Å, and the distance between water molecules was 2.6 Å.
Table 1.
Re-evaluation of copper sites in CBC enzyme structures.
Fig 5.
Re-refinement of publish CBC enzyme crystal structures.
A The copper site of the deposited 1BT3 (catechol oxidase from Ipomoea batatas) shows a positive peak of the Fo−Fc electron density (in green) in PDB_REDO-calculated maps. The distance between copper ions was 2.9 Å, and the Cu-O distances were both 2.0 Å. B Calculated Fo−Fc difference-Fourier omit map (in green) for oxygen in 1BT3. C Calculated 2Fo−Fc Fourier map (in blue, 1σ contour level) for the copper site in the re-refined structure of 1BT3. Two oxygen atoms were refined between the copper ions. The distance between copper ions was 3.0 Å, and all the Cu-O distances were 1.9 Å. D The copper site of the deposited 2AHL (tyrosinase from Streptomyces castaneoglobisporus) shows peaks of positive Fo−Fc electron density (in green) around the water in the PDB_REDO-calculated maps. E Copper site of deposited 2P3X with the Cu-O-Cu unit shows a peak of Fo−Fc difference electron density (in green) in PDB_REDO-calculated maps. F Copper site of deposited 4J6T (tyrosinase from Bacillus megaterium) with one water molecule shows a peak of Fo−Fc difference electron density (in green) in PDB_REDO-calculated maps. Molecule A is shown. G The calculated Fo−Fc difference-Fourier omit map (in green) for water in 4J6T. H Calculated 2Fo−Fc Fourier map (in blue) for the copper site in the re-refined structure of 4J6T. Peroxide ion was refined between the copper ions. The difference maps are all shown in 3σ contour level.
Fig 6.
Different forms of coupled binuclear copper sites.
Table 2.
Data collection and structure refinement statistics for AoCO4 crystals.