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Enzymes as Catalysts

Substance that increase the rate of a chemical reaction

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The Cheese Effect

The Cheese Effect

Credit: Nate Steiner
Source: http://www.flickr.com/photos/nate/412768397/
License: CC BY-NC 3.0

Eating cheese can cause a headache? A wife of a physician got serious migraine headaches whenever she ate cheese. She was also being treated with monoamine oxidase inhibitors because of her depression. What do these two seemingly unrelated factors have to do with headaches?

Amazing But True

  • Serotonin is a complex cyclic molecule that contains both a primary and a secondary amine in its structure. This molecule is synthesized from the amino acid tryptophan. Serotonin in the brain helps transmit nerve signals from one part of the brain to another. It is inactivated by the enzyme monoamine oxidase (MAO).
  • License: CC BY-NC 3.0

    Serotonin affects many of our daily activities. Maintaining the right level of serotonin helps us feel normal [Figure2]

  • Many psychiatrists believe that some cases of depression result from a decrease in serotonin in the brain. By giving MAO inhibitors to the patient, the thinking is that the serotonin breakdown will be decreased and serotonin levels in the brain will rise, somehow alleviating the depression. If the MAO is inhibited, it cannot convert as much serotonin to inactive product, so more serotonin will be available in the brain.
  • MAO inhibitors are no longer the drug of choice, although they can be effective in some cases. Newer drugs, known as selective serotonin reuptake inhibitors (SSRI), also increase serotonin levels, but by a different mechanism. These drugs are more specific and thought to be more effective.
  • Tyramine is an amine compound formed from the amino acid tyrosine. In the presence of MAO inhibitors, tyramine will accumulate and trigger release of several compounds that produce blood vessel constriction, giving rise to high blood pressure.
  • Watch this video to learn mroe about migraine headaches: 


Show What You Know

Use the links below to learn more about the cheese effect. Then answer the following questions.

  1. Where is 90% of the serotonin in the body found?
  2. Do blood levels of serotonin reflect serotonin brain concentrations?
  3. Does exercise increase mood?
  4. Which form of MAO is inhibited most, causing the “cheese effect”?
  5. What are two factors that may raise the amount of tyramine in high-protein foods?

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Image Attributions

  1. [1]^ Credit: Nate Steiner; Source: http://www.flickr.com/photos/nate/412768397/; License: CC BY-NC 3.0
  2. [2]^ License: CC BY-NC 3.0

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