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Description
Asparagine is a nonessential amino acid, which means that
it is manufactured from other amino acids in the liver; it does not have to be
obtained directly through the diet.
There is no suggested need for asparagine supplementation
presently available in the literature. Asparagine is interrelated with the
amino acid aspartic acid. Low levels of asparagine may indicate poor metabolism
or synthesis of aspartic acid, which can result in the inability to properly
synthesize and excrete urea, which is the major waste product of excess dietary
protein. The inability to excrete urea can result in buildup of
nitrogen-containing toxic metabolites that can lead to confusion, headaches,
depression, irritability, or, in extreme cases, psychosis.
Deficiencies of a nonessential amino acid will not occur
if a well-balanced diet is consumed because the intake of proper foods will
allow the body to produce exactly the amount of amino acid required to function
optimally.
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Method of
Action
Prior to 1940, amino acids were generally regarded as
relatively-stable nutrient building blocks. In the 1940s and 50's that concept
was abandoned when it was found that the nitrogen atom in amino acids such as
aspartic and glutamic acids could be rapidly converted from one amino acid
carbon skeleton to another. The process by which these nitrogen atoms are
exchanged is called transamination and is dependent upon the coenzyme pyridoxal
pyrophosphate, which is derived from vitamin B-6. Both aspartic acid and
glutamic acid can incorporate ammonia, thereby resulting in the production of
asparagine and glutamine, respectively. It soon became apparent that asparagine
and glutamine are soluble, nontoxic carriers of additional ammonia in the form
of their amid groups. An active enzyme converts aspartate and ammonia to
asparagine and glutamate and ammonia to glutamine. The nitrogen in glutamine is
used in a great variety of biochemical processes, including the formation of
carbamoyl phosphate used in the urea cycle and the production of purines, which
are used in DNA and RNA.
Glutamate, glutamine, and aspartate also play central
roles in the removal of all nitrogen from organic compounds. The exchange of
nitrogen by transamination is reversible so that when the body is properly
managing glutamate and aspartate, there is the exchange of nitrogen from one
source, ultimately, from the urea cycle and the elimination in the urine as
urea.
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