194 12.81 Zinc Functions
Zinc is a cofactor for up to 300 enzymes in the body1. Enzymes that use zinc as a cofactor are known as metalloenzymes.
Zinc is a cofactor for the antioxidant enzyme superoxide dismutase that converts superoxide to hydrogen peroxide, as shown below.
Alcohol dehydrogenase uses 4 zincs per enzyme. Its role in ethanol metabolism is shown below2.
Delta-aminolevulinic acid dehydratase (ALA dehydrogenase), which is involved in heme synthesis, uses 8 zincs/enzyme to form porphobilinogen, as shown below2.
The enzyme that cleaves the extra glutamates from folate so that it can be taken up into the enterocyte is a metalloenzyme2. The cleavage of folate is shown in the figure below.
Other notable metalloenzymes include DNA and RNA polymerase2.
Zinc is also important for the formation of zinc fingers in proteins. Zinc fingers help proteins bind to DNA2.
Zinc is also important for growth, immune function, and reproduction2.
A recent Cochrane review concluded that when taken within 24 hours of the onset of symptoms, that zinc lozenges or syrup results in a significant decrease in the duration and severity of common cold symptoms7. Thus, commonly used zinc lozenges may be an effective way to combat the common cold. However, large amounts of zinc consumption can be problematic for copper and ultimately iron levels in the body, as described in the copper section.
References & Links
1. Byrd-Bredbenner C, Moe G, Beshgetoor D, Berning J. (2009) Wardlaw’s perspectives in nutrition. New York, NY: McGraw-Hill.
2. Gropper SS, Smith JL, Groff JL. (2008) Advanced nutrition and human metabolism. Belmont, CA: Wadsworth Publishing.
3. http://en.wikipedia.org/wiki/File:Ethanol_flat_structure.png
4. https://en.wikipedia.org/wiki/Acetaldehyde#/media/File:Acetaldehyde-2D-flat.svg
5. http://en.wikipedia.org/wiki/File:Heme_synthesis.png
6. http://en.wikipedia.org/wiki/File:Zinc_finger_rendered.png
7. Singh M, Das RR. (2011) Zinc for the common cold (Review). The Cochrane Collaboration.