Indicators
A small non-essential amino acid in humans, Alanine is one of the most widely used for protein construction and is involved in the metabolism of tryptophan and vitamin pyridoxine. Alanine is an important source of energy for muscles and central nervous system, strengthens the immune system, helps in the metabolism of sugars and organic acids, and displays a cholesterol-reducing effect in animals. (NCI04)
Indicators
A family of pyridoxal phosphate-dependent enzymes involved in cellular nitrogen metabolism, amino acid metabolism, and liver gluconeogenesis. Alanine aminotransferase specifically and reversibly catalyzes the transfer of an amino group from L-alanine to alpha-ketoglutarate forming pyruvate and L-glutamate.
Indicators
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)
Indicators
A family of pyridoxal phosphate-dependent enzymes involved in amino acid metabolism and in the urea and tricarboxylic acid cycles. Aspartate aminotransferase specifically and reversibly catalyzes the transfer of an amino group from L-aspartate to alpha-ketoglutarate forming oxaloacetate and L-glutamate.
Indicators
An amino acid derivative. Carnitine facilitates long-chain fatty acid entry into mitochondria, delivering substrate for oxidation and subsequent energy production. Fatty acids are utilized as an energy substrate in all tissues except the brain.
Indicators
A non-essential amino acid. In hepatocytes, L-citrulline is synthesized in the urea cycle by the addition of carbon dioxide and ammonia to ornithine. L-citrulline is converted into L-arginine by the enzymes argininosuccinate synthetase and argininosuccinate lyase in the presence of L-aspartate and ATP. Subsequently, L-arginine is converted to nitric oxide by nitric oxide synthase and L-citrulline is regenerated as a by-product.
Indicators
A non-essential sulfur-containing amino acid in humans, related to cystine, Cysteine is important for protein synthesis, detoxification, and diverse metabolic functions. Found in beta-keratin, the main protein in nails, skin, and hair, Cysteine is important in collagen production, as well as skin elasticity and texture. Also required in the manufacture of amino acid taurine, Cysteine is a component of the antioxidant glutathione, and plays a role in the metabolism of essential biochemicals such as coenzyme A, heparin, and biotin. (NCI04)
Indicators
Not considered one of the 20 amino acids, Cystine is a sulfur-containing derivative obtained from oxidation of cysteine amino acid thiol side chains. It functions as an antioxidant and protects tissues against radiation and pollution, slowing the aging process. It also aids protein synthesis. Cystine is abundant in many proteins of skeletal tissues and skin, and found in insulin and digestive enzymes chromotrypsinogen A, papain, and trypsinogen. (NCI04)
Indicators
A collective term for pteroylglutamic acids and their oligoglutamic acid conjugates. As a natural water-soluble substance, folic acid is involved in carbon transfer reactions of amino acid metabolism, in addition to purine and pyrimidine synthesis, and is essential for hematopoiesis and red blood cell production. (NCI05)
Indicators
GGT participates in the transfer of amino acids across the cellular membrane and in glutathione metabolism. High concentrations are found in the liver, bile ducts, and the kidney. A test that measures the amount of GGT in the blood is used to detect diseases of the liver, bile ducts, and kidney; and to differentiate liver or bile duct (hepatobiliary) disorders from bone disease.
Indicators
A non-essential alpha-amino acid and excitatory neurotransmitter. Glutamic acid can serve as a precursor for the synthesis of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA).
Indicators
A nonessential amino acid. Glutamine can donate the ammonia on its side chain to the formation of urea (for eventual excretion by the kidneys) and to purines (necessary for the synthesis of nucleic acids). Glutamic acid-to-glutamine conversion, in which an ammonia group is added to glutamic acid (catalyzed by glutamine synthase), is of central importance in the regulation of toxic levels of ammonia in the body. This agent is a substrate for the production of both excitatory and inhibitory neurotransmitters (glutamate and GABA) and is also an important source of energy for the nervous system. Glutamine may become a conditionally essential amino acid during certain catabolic states.