Figure 5: Electron transfer chain and plastocyanin binding.
Residues 18 -47 of plant PsaF, which include the 18 residues
exclusive to eukaryotes and that form a helix -loop -helix
domain, are coloured red. A cluster of four negatively charged
residues (red) on the surface of plastocyanin (green) interacts
with three lysines (blue) from the N terminus of PsaF, two of
which are from the extra 18 residues. The two tryptophan
residues (indicated by an arrow) crucial for the electron
transfer from the reduced copper to the oxidized P, and
that contribute to the hydrophobic interaction with
plastocyanin, are shown as spherical atoms (cyan and magenta).
The histidine residue that coordinates the copper atom in
plastocyanin is in blue.
The above figure is reprinted
by permission from Macmillan Publishers Ltd: