Asparagine was first isolated in 1806 from asparagus juice, from where it got its name, becoming the first amino acid to be isolated. Asparagine is one of the principal and frequently the most abundant of the amino acids involved in the transport of nitrogen. Asparagine is the beta-amide of aspartic acid, synthesized from aspartic acid and adenosine triphosphate (ATP). The main function of asparagine is converting one amino acid into another via amination, the process by which an amine group is introduced into an organic molecule, and transamination, the reaction when an amine group is transferred to an alpha-ketoacid. Asparagine is required by the nervous system and plays an important role in the synthesis of ammonia. Measurement of asparagine is included in the Amino Acids, Plasma and Amino Acids, Urine tests along with 23 other amino acids.
Asparagine (Asn/N) is a non-essential amino acid, meaning that it can be synthesized through specific metabolic pathways in humans and does not need to be obtained from the diet. The precursor of asparagine is oxaloacetate which is converted to aspartic acid with the help of an enzyme (transaminase). The enzyme transfers the amino group from glutamate to oxaloacetate and α-ketoglutarate and aspartic acid are produced. The enzyme asparagine synthetase produces asparagine, AMP, glutamate, and pyrophosphate from aspartate, glutamine, and ATP.
Since the asparagine side chain can form very strong hydrogen bonds with the peptide chain, asparagine is often found in large numbers near the beginning and end of α-helices and at the bends in β-sheets (the α-chains and β-sheets refer to the secondary structure of proteins). Glutamine, because it has an extra methylene group and more conformational entropy, is less useful in this regard.
Asparagine also provides binding sites for N-linked glycosylation, the modification of protein chains by the addition of carbohydrate chains. Acrylamide is produced by the reaction between asparagine and reducing sugars or reactive carbonyls during the cooking of foods when they are heated to high temperatures. This happens mainly in baked goods such as French fries, potato chips, and roasted coffee.
Asparagine was first isolated in 1806 from asparagus juice, where it is abundant – hence its name – and was the first amino acid to be isolated. The odor observed in the urine of some people after eating asparagus is attributed to a by-product of the metabolic breakdown of asparagine, asparagine-amino-succinic acid monoamide, but it may also be due to other substances.
Asparagine is found in high concentrations in animal products such as dairy, beef, poultry, eggs, fish, and seafood, and in plant products such as asparagus, potatoes, legumes, nuts, soy, and whole grains.