Asparagine (Asn) or L-asparagine is an alpha-amino acid. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon).  Amino acids are organic compounds that contain amino (‚ÄìNH2) and carboxyl (‚ÄìCOOH) functional groups, along with a side chain (R group) specific to each amino acid. L-asparagine is one of 20 proteinogenic amino acids, i.e., the amino acids used in the biosynthesis of proteins. Asparagine is found in all organisms ranging from bacteria to plants to animals. In humans, asparagine is not an essential amino acid, which means that it can be synthesized from central metabolic pathway intermediates in humans and is not required in the diet. The precursor to asparagine is oxaloacetate. Oxaloacetate is converted to aspartate using a transaminase enzyme. This enzyme transfers the amino group from glutamate to oxaloacetate producing alpha-ketoglutarate and aspartate. The enzyme asparagine synthetase produces asparagine, AMP, glutamate, and pyrophosphate from aspartate, glutamine, and ATP. In the asparagine synthetase reaction, ATP is used to activate aspartate, forming beta-aspartyl-AMP. Glutamine donates an ammonium group which reacts with beta-aspartyl-AMP to form asparagine and free AMP. Since the asparagine side chain can make efficient hydrogen bond interactions with the peptide backbone, asparagines are often found near the beginning and end of alpha-helices, and in turn motifs in beta sheets. Its role can be thought as "capping" the hydrogen bond interactions which would otherwise need to be satisfied by the polypeptide backbone. Asparagine also provides key sites for N-linked glycosylation, a modification of the protein chain that is characterized by the addition of carbohydrate chains. A reaction between asparagine and reducing sugars or reactive carbonyls produces acrylamide (acrylic amide) in food when heated to sufficient temperature (i.e. baking). These occur primarily in baked goods such as French fries, potato chips, and roasted coffee. Asparagine was first isolated in 1806 from asparagus juice --hence its name. Asparagine was the first amino acid to be isolated. The smell observed in the urine of some individuals after the consumption of asparagus is attributed to a byproduct of the metabolic breakdown of asparagine, asparagine-amino-succinic-acid monoamide. However, some scientists disagree and implicate other substances in the smell, especially methanethiol.