Copper-Coping with Dioxygen - Biological Inorganic Chemistry - page 286

FIGURE 14.7 Arrangement of the domains within the subunit structures of different type 3 copper proteins. (a) Limulus polyphemus
haemocyanin, (b) Octopus dofleini FU g haemocyanin, (c) Streptomyces castaneoglobisporus tyrosinase, (d) Ipomoea batatas catechol oxidase,
(e) Sequence comparison (same colour code: domain I (green), domain II (red), domain III (cyan); copper centres are indicated by the hatched
blocks, the blocking residues are shown as black bars). In all cases, the domains are parts of the subunit with the exception of Streptomyces
tyrosinase, where an associated caddie protein (MelC1) provides Y98. (From Decker, Schweikardt, Nillius, Salzbrunn, Jaenicke, & Tuczek,

2007 . Copyright 2007, with permission from Elsevier.)

FIGURE 14.8 Dioxygen binding and (hypothetical) coordination of the substrate at the active site of Streptomyces tyrosinase. The distances
are given to indicate whether a reaction may be possible or not. In (a) the distance between the hydroxyl group and Cu A is too large for any
reaction. After movement to the coordination point (grey) above Cu A , the distance is shortened reasonably to allow a reaction. (a) shows the
initial configuration after approach to the active site, based on the crystal structure of Streptomyces tyrosinase; (b) shows the shift of the
substrate to Cu A ; Coppers: blue, histidines: green, dioxygen molecule: red, monophenolic substrate: cyan (its oxygen black), equatorial
coordination of Cu A and Cu B : yellow frame, axial coordination of Cu A and Cu B : yellow lines; trans-axial coordination of Cu A : grey dot. (From
Decker et al., 2007 . Copyright 2007, with permission from Elsevier.)