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.
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.
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.
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.
Cytochrome c oxidase (complex IV) in the electron transport chain is a copper-containing enzyme that reduces oxygen to form water, as shown below1.
Lysyl oxidase, an enzyme that is important for cross-linking between structural proteins (collagen and elastin), requires copper as a cofactor1.
References & Links
1. Gropper SS, Smith JL, Groff JL. (2008) Advanced nutrition and human metabolism. Belmont, CA: Wadsworth Publishing.