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.
![](https://s3-us-west-2.amazonaws.com/courses-images/wp-content/uploads/sites/2569/2017/10/27164429/10000000000003AB0000021C44A7B1B0.png)
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.
![](https://s3-us-west-2.amazonaws.com/courses-images/wp-content/uploads/sites/2569/2017/10/27164432/1000000000000473000002F5A403A9C6.png)
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.
![](https://s3-us-west-2.amazonaws.com/courses-images/wp-content/uploads/sites/2569/2017/10/27164434/1000020100000108000001467EB44654.png)
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.
![](https://s3-us-west-2.amazonaws.com/courses-images/wp-content/uploads/sites/2569/2017/10/27164436/100000000000032E0000024E50F24AA2.png)
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.
![](https://s3-us-west-2.amazonaws.com/courses-images/wp-content/uploads/sites/2569/2017/10/27164438/10000000000003B9000001D748EB40C8.png)
Figure 12.915 Cytochrome c oxidase (complex IV)
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.
2. http://en.wikipedia.org/wiki/File:Catecholamines_biosynthesis.svg
3. http://wikidoc.org/index.php/File:ETC.PNG