This news item was adapted by students Erin Bussard, Amanda Veatch, Christine O'Gara, Andrew Probert, and Christopher Massat as part of their Chemistry 212 Project in WS2000 under the guidance of Prof. Rainer Glaser.
Glaser's "Chemistry is in the News"
Homocysteine is an intermediary metabolite of the amino acid methionine. Homocysteine is created during meat catabolism, and is present in the blood. The IUPAC name is 2-Amino-4 mercapto butyric acid, and you can find its structure on ChemFinder.
Homocysteine is found in all people in varying levels. Women generally have lower levels than men do. WebMDHealth says that optimal levels are 12 micromoles/liter of blood or less. Peopl e aren't certain what levels constitute a high risk, but it is thought to begin at 12-16 micromoles/liter. High homocysteine levels are caused by the consumption of proteins, as homocysteine is a byproduct of the breakdown of meat. High homocysteine can c ause many problems, but especially increased risk of stroke, heart disease, "sticky" arteries, atherosclerosis, preeclampsia, and Alzheimer's disease.
The exact mechanism for how homocysteine contributes to these disorders is still under discussion. A widely accepted theory says that homocysteine damages artery walls, making them "sticky" and more susceptible to plaque buildup. This damage to arteries can contribute to the aforementioned heart disorders. Homocysteine is also believed to interfere with nitric oxide in the blood.
Homocysteine can be measured through a simple blood test. Most hospital labs can measure homocysteine from a blood sample. At the present time, doctors aren't recommending testing unless the individual is already at risk for heart disease. Not having o ther risk factors doesn't make it safe to have high homocysteine levels, because the risk from homocysteine was independent of other risks, but testing is still not widespr ead at t his time.
Folic acid and B-vitamins are the best means by which to lower homocysteine levels, so listen to what your mother said about eating healthy. Fruits, vegetables, and cereals are all good sources of these nutrients. Vitamin supplements also contain folic acid and B-vitamins.
Pertinent Text References
Chapter 19. Amines.
Chapter 24. Amino Acids, Peptides and Proteins.
Chapter 24-5. Synthesis of Amino Acids
Question 1: Some sources call homocysteine an amino acid instead of the product of amino acid breakdown.. Is homocysteine an amino acid? What defines an amino acid?
Question 2: The IUPAC name for homocysteine is 2-Amino-4-mercaptobutyric acid. Draw the structure of this molecule. Could this molecule be optically active?
Question 3: Methionine breaks down in meat metabolism and homocysteine is one of its products. Besides methionine, which amino acids are similar in structure to homocysteine?
Question 4: Are high homocysteine levels a better predictor of heart disease than high cholesterol levels? Experts differ in opinion. What do you think?
Question 5: Fully one fifth of the worlds' population is starving or malnourished, and meat requires far more land and resources to produce than non-meat food items. Why are we still eating so much meat that is correlated with heart disease?