Amino Acids Go Many Different
acids have biological functions other than as parts of proteins and
oligopeptides. The following examples illustrate some of these functions for a
few of the amino acids.
products sold in health food stores feature the presence of the branched-chain
amino acids isoleucine, leucine, and valine. These are essential amino acids in the sense that the body cannot synthesize
them. Under normal circumstances, a diet with adequate protein intake provides
enough of all the essential amino acids. Athletes involved in intensive
training want to prevent muscle loss and to increase muscle mass. As a result,
they take protein supplements and pay particular attention to branched-chain
amino acids. (These three amino acids are by no means the only essential ones,
but they are mentioned specifically here.)
glutamate, or MSG, is a derivative of glutamic acid that finds wide use as a
flavor enhancer. MSG causes a physiological reaction in some people, with
chills, headaches, and dizziness resulting. Because many Asian foods contain
significant amounts of MSG, this problem is often referred to as Chinese restaurantsyndrome.
acid group of histidine is removed, it is converted to histamine, which is a
potent vasodilator, increasing the diameter of blood vessels. Histamine, which
is released as part of the immune response, increases the localized blood
volume for white blood cells. This results in the swelling and stuffiness that
are associated with a cold. Most cold medications contain antihistamines to
overcome this stuffiness.