ChEBI: L-arginine is an L-alpha-amino acid that is the L-isomer of arginine. It has a role as a nutraceutical, a biomarker, a micronutrient, an Escherichia coli metabolite and a mouse metabolite. It is a glutamine family amino acid, a proteinogenic amino acid, an arginine and a L-alpha-amino acid. It is a conjugate base of a L-argininium(1+). It is a conjugate acid of a L-argininate. It is an enantiomer of a D-arginine.NCI Thesaurus (NCIt): Arginine is an essential amino acid in juvenile humans, Arginine is a complex amino acid, often found at active site in proteins and enzymes due to its amine-containing side chain. Arginine may prevent or treat heart and circulatory diseases, combat fatigue, and stimulate the immune system. It also boosts production of nitric oxide, relaxing blood vessels, and treating angina and other cardiovascular problems. Arginine is also an important intermediate in the urea cycle and in detoxification of nitrogenous wastes. (NCI04)