glutamic acid(redirected from Excitatory amino acid agents)
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glutamic acid(glo͞otăm`ĭk), organic compound, one of the 20 amino acidsamino acid
, any one of a class of simple organic compounds containing carbon, hydrogen, oxygen, nitrogen, and in certain cases sulfur. These compounds are the building blocks of proteins.
..... Click the link for more information. commonly found in animal proteins. Only the l-stereoisomer occurs in mammalian proteins. Like aspartic acidaspartic acid
, organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer participates in the biosynthesis of proteins.
..... Click the link for more information. , glutamic acid has an acidic carboxyl group on its side chain which can serve as both an acceptor and a donor of ammonia, a compound toxic to the body. Once glutamic acid has coupled with ammonia, it is called glutamineglutamine
, organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer occurs in mammalian protein.
..... Click the link for more information. and can as such safely transport ammonia to the liver, where the ammonia is eventually converted to ureaurea
, organic compound that is the principal end product of nitrogen metabolism in most mammals. Urea was the first animal metabolite to be isolated in crystalline form; its crystallization was described in the early 18th cent.
..... Click the link for more information. for excretion by the kidneys. Free glutamic acid (that not incorporated into proteins) can also be converted reversibly to α-ketoglutaric acid, an intermediate in the Krebs cycle, and as such can be degraded to carbon dioxide and water, or transformed into sugars. The acidic side chain of glutamic acid confers one negative charge under most conditions to proteins in which this amino acid is found, thus increasing the water solubility of the protein. Monosodium glutamate (MSG), the monosodium salt of l-glutamic acid, is widely used as a condiment. The amino acid was isolated from wheat gluten in 1866 and chemically synthesized in 1890. It is not essential to the human diet, since it can be synthesized in the body from the common intermediate α-ketoglutaric acid.
an amino acid, COOH—CH2—CH2— CH(NH2)—COOH. Water-soluble crystals. Melting point, 202° C. It is a component of proteins and of a number of important low-molecular-weight compounds (for example, glutathione and folic acid). The natural form is the D(+) isomer. Glutamic acid is a nonessential amino acid for animals. It is contained in large amounts in casein, gelatin, and gluten. Together with the corresponding γ-monoamide, glutamine, it comprises about one-third of the total free amino acids in blood plasma. The reaction glutamic acid + NH3 + ATP ⇌ glutamine + ADP + Pinorg. is catalyzed by the enzyme glutamine synthetase, which belongs to the lyase group. This reaction results in the binding of excess ammonia in animal and vegetable tissues. Thus, glutamine transports ammonia to the site of its detoxification (mostly in the kidneys and liver). Glutamine also serves as an amino-group reserve and is a component of proteins. The glutamine-glutamic-acid system plays a particularly important role in metabolism. Glutamic acid also takes part in other important metabolic processes, such as transamination (where, with as partic acid, it is an invariable participant), in oxidative deamination leading to the formation of α-ketoglutaric acid (which is involved in the tricarboxylic acid cycle), in decarboxylation leading to the formation of the important neurotropic agent γ-aminobutyric acid, and in many syntheses, including glutathione, glucose, and ornithine.
Glutamic acid is utilized in the food industry as a sodium salt for improving the taste and nutritional value of foods. It is used in medicine in tablets, powders, and pastes, as well as in solutions (for intravenous infusion) in the treatment of some mental and nervous diseases. The calcium and magnesium salts of glutamic acid are also prescribed.
A. A. BOLDYREV