Amino acid
One of the 20 building blocks of protein. The sequence of amino acids in a protein and, hence, the function of that protein are determined by the genetic code in the DNA. Amino acids are molecules that (in technical terms) contain a basic amino (NH2) group, an acidic carboxyl (COOH) group and a side chain attached to an alpha carbon atom. The 20 amino acids are alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine. The term "amino acids" dates to the middle of the 19th century. The idea that amino acids are "Bausteine" (building stones) came from the Nobel Prize winning German biochemist Albrecht Kossel (1853-1927).
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An organic acid in which one of the hydrogen atoms on a carbon atom has been replaced by NH2. Usually refers to an aminocarboxylic acid. However, taurine is also an a.. SEE ALSO: α-a..
- acidic a. an A. with a second acid moiety, e.g., glutamic acid, aspartic acid, cysteic acid.
- activated a. SYN: aminoacyl adenylate.
- basic a. an a. containing a second basic group (usually an amino group); e.g., lysine, arginine, ornithine. SYN: dibasic a..
- a. dehydrogenases enzymes catalyzing the oxidative deamination of amino acid s to the corresponding oxo (keto) acids; two relatively nonspecific varieties exist, l and d, for which l-amino acids and d-amino acids are the respective substrates; the products include NH3 and a reduced hydrogen acceptor (NADH in the l case); a. dehydrogenases of greater specificity exist ( e.g., glycine dehydrogenase). Cf.:a. oxidases.
- dibasic a. SYN: basic a..
- essential amino acid s α-amino acid s nutritionally required by an organism and which must be supplied in its diet ( i.e., cannot be synthesized by the organism) either as free a. or in proteins.
- nonessential amino acid s those amino acid s that may be synthesized by an organism and are thus not required as such in its diet.
- nonpolar a. an α-a. in which the functional group attached to the α-carbon ( I.E., R in RCH(NH2)COOH) has hydrophobic properties; E.G., valine, leucine, α-aminobutyrate.
- a. oxidases flavoenzymes oxidizing, with O2 and H2O, either l- or d-amino acids specifically, to the corresponding 2-keto acids, NH3 and H2O2. Cf.:a. dehydrogenases, yellow enzyme.
- polar a. an α-a. in which the functional group attached to the α-carbon ( i.e., R in RCH(NH2)COOH) has hydrophilic properties; e.g., serine, cysteine, homocysteine.

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amino acid n an amphoteric organic acid containing the amino group NH2 esp ALPHA-AMINO ACID

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an organic compound containing an amino group (-NH2) and a carboxyl group (-COOH). Amino acids are fundamental constituents of all protein. Breakdown of proteins found in the body yields the following amino acids: alanine, arginine, asparagine, aspartic acid, cysteine, cystine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine. Some of these amino acids can be synthesized by the body; others, the essential amino acid, must be obtained from protein in the diet. Certain amino acids present in the body are not found in proteins; these include citrulline, ornithine, taurine, and gamma-aminobutyric acid acid.

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see at amino.

Medical dictionary. 2011.

Look at other dictionaries:

  • amino acid — n. 1. any of a large group of organic acids containing a carboxyl group, COOH, and an amino group, NH2 2. any of the 25 amino acids that link together into polypeptide chains to form proteins that are necessary for all life: in general, they are… …   English World dictionary

  • amino acid — ► NOUN ▪ any of a class of about twenty organic compounds which form the basic constituents of proteins and contain both acid and amine groups …   English terms dictionary

  • amino acid — amino acid. См. аминокислота. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • amino acid —  Amino Acid  Аминокислота   Органическое соединение, в молекуле которого одновременно содержатся карбоксильная и аминная группы; в 20 природных аминокислотах обе группы связаны с одним и тем же атомом C.   Аминокислоты объединяются амидными… …   Толковый англо-русский словарь по нанотехнологии. - М.

  • Amino acid — This article is about the class of chemicals. For the structures and properties of the standard proteinogenic amino acids, see Proteinogenic amino acid. The generic structure of an alpha amino acid in its unionized form …   Wikipedia

  • amino acid — Biochem. any of a class of organic compounds that contains at least one amino group, NH2, and one carboxyl group, COOH: the alpha amino acids, RCH(NH2)COOH, are the building blocks from which proteins are constructed. Cf. essential amino acid.… …   Universalium

  • amino acid — n. Biochem. any of a group of organic compounds containing both the carboxyl (COOH) and amino (NH2) group, occurring naturally in plant and animal tissues and forming the basic constituents of proteins. Etymology: AMINE + ACID * * * amino acid… …   Useful english dictionary

  • amino acid — UK [əˌmiːnəʊ ˈæsɪd] / US [əˌmɪnoʊ ˈæsɪd] noun [countable] Word forms amino acid : singular amino acid plural amino acids biology one of the substances in the body that combine to make proteins …   English dictionary

  • amino acid — A compound containing both amino ( NH2) and carboxyl ( COOH) groups. In particular, any of 20 basic building blocks of proteins having the formula NH2 CR COOH, where R is different for each specific amino acid. See: annex 3 …   Glossary of Biotechnology

  • amino acid — noun Amino acid is used before these nouns: ↑sequence …   Collocations dictionary

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