---

L-asparagine

Asparagine is a non-essential amino acid, and specifically is the beta amide of aspartic acid that exists in both the d(+) and 1(-) isomeric forms. It is widely distributed in plants and animals as it is found both in free form and as a component in proteins. The amino acid has useful applications as a flavor ingredient, and in medicine and biochemical research. Asparagine and glutamine exist in two enantiomorphic forms D and L as a result of the presence of an asymmetric centre in the 2-position on the carbon atom carrying the amino group. Asparagine plays an important role as a transport form of nitrogen and in many plants, it is the principle compound involved in the transfer of nitrogen from the roots into the transpiration stream. In plants asparagine is formed from glutamine, aspartate and ATP catalyzed by the asparagine synthetase ASN whereby glutamate, AMP and pyrophosphate are formed as by-products. Asparagine is the major nitrogen transport compound which is synthesized when a plant is faced with excess ammonia rather than nitrate. In higher plants, nitrogen assimilated from the soil must be incorporated into organic form for transport to the growing plant. The amides, asparagine and glutamine, are the two major nitrogen transport compounds in most higher plants. These amides function to deliver nitrogen to and from plant organs at various stages of plant development. Asparaginases are enzymes which catalyze the deamidation of L-asparagine (asparaginase activity) and L-glutamine (glutaminase activity). L-glutamine serves as the amide donor in purine biosynthesis, as well as other transamination reactions, and hence plays a role in DNA and cyclic nucleotide metabolism.

---