Copper has a number of functions that are described and shown below.
Two copper-containing proteins, ceruloplasmin and hephaestin, oxidize Fe2+ to Fe3+. Fe3+ is the form that binds to transferrin, as shown below1.
Figure 12.911 Transport and uptake of iron
Because copper is needed for this function, it is important for iron absorption. Copper is also a cofactor for superoxide dismutase, which converts superoxide to hydrogen peroxide, as shown below.
Figure 12.912 Superoxide dismutase uses zinc as a cofactor
Copper is also needed for hormone synthesis. For example, it is a cofactor for dopamine beta-hydroxylase, which converts dopamine to norepinephrine, as shown below1.
Figure 12.913 Dopamine beta-hydroxylase requires copper2
Hopefully the following example looks vaguely familiar because we talked about this pathway in the the vitamin C functions subsection. Ascorbic acid reduces Cu2+ back to Cu1+ so that this enzyme can continue to function, as shown below1. This is analogous to how ascorbic acid reduces Fe3+ back to Fe2+ so proline and lysyl hydroxylases can continue to function.
Figure 12.914 Dopamine beta-hydroxylase
Cytochrome c oxidase (complex IV) in the electron transport chain is a copper-containing enzyme that reduces oxygen to form water, as shown below1.
Figure 12.915 Cytochrome c oxidase (complex IV)3
Lysyl oxidase, an enzyme that is important for cross-linking between structural proteins (collagen and elastin), requires copper as a cofactor1.
References & Links
- Gropper SS, Smith JL, Groff JL. (2008) Advanced nutrition and human metabolism. Belmont, CA: Wadsworth Publishing.