Copper-Coping with Dioxygen - Biological Inorganic Chemistry - page 293

FIGURE 14.15 Structure of M. capsulatus (Bath) pMMO protomer (PDB accession code 1YEW). The N-terminal cupredoxin domain of
pmoB (spmoBd1) is shown in purple, the C-terminal cupredoxin domain of pmoB (spmoBd2) is shown in green, and the two transmembrane
helices are shown in blue. In the recombinant spmoB protein, spmoBd1 and spmoBd2 are connected by a GKLGGG sequence linking residues
172 and 265 instead of the two transmembrane helices. Copper ions are shown as cyan spheres and ligands are shown as ball-and-stick
representations. The pmoA (transparent light green) and pmoC (transparent light blue) subunits are composed of transmembrane helices. The
location of the zinc ion (grey sphere) has been proposed to house a di-iron centre. A hydrophilic patch of residues marked with an asterisk is the
site of a proposed tricopper centre. (From Balasubramanian et al., 2010 . Copyright 2010 with permission from Nature.)
cytochrome c oxidase subunit II. A third metal centre, occupied by Zn in the crystal, is located within the membrane
( Balasubramanian, Smith, Rawat, Yatsunyk, Stemmler, & Rosenzweig, 2010 ).
While nitrite reductases in many bacteria are haem proteins, some are copper-containing homotrimers which
bind three type I and three type II copper centres The type 1 copper centre serves to transfer electrons from donor
proteins to the type 2 centre which has been proposed to be the site of substrate binding.