| amino acid substitution | The naturally occurring or experimentally induced replacement of one or more amino acids in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties. (12 Dec 1998) |
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| amino acid transmitter | <biochemistry> Amino acids released as neurotransmitter substances from nerve terminals and acting on postsynaptic receptors for example _ aminobutyric acid (GABA) and glycine that are fast inhibitory transmitters in the mammalian central nervous system. Glutamate and aspartate mediate fast excitatory transmission. Strychnine (for glycine) and bicuculline for GABA) are blocking agents for amino acid action. (18 Nov 1997) |
| amino acids | Organic compounds that generally contain an amino (-nh2) and a carboxyl (-cooh) group. Twenty alpha-amino acids are the subunits which are polymerised to form proteins. (12 Dec 1998) |
| amino acids, branched-chain | Amino acids which have a branched carbon chain. (12 Dec 1998) |
| amino acids, cyclic | A class of amino acids characterised by a closed ring structure. (12 Dec 1998) |
| amino acids, peptides, and proteins | Amino acids and chains of amino acids connected by peptide linkages. (12 Dec 1998) |
| amino acyl-tRNA ligases | <enzyme> Any of the group of ligases that catalyses the ATP-driven formation of a bond between an amino acid and a trna, activating the amino acids as a step in protein synthesis. Individual enzymes are highly specific for one amino acid and for any trna corresponding to that amino acid. Registry number: EC 6.1.1. (12 Dec 1998) |
| amino alcohols | Compounds possessing both a hydroxyl (-oh) and an amino group (-nh2). (12 Dec 1998) |
| amino group | <biochemistry> An -NH2 group. Organic compounds which have this group are called amines. (09 Oct 1997) |
| amino sugar | <biochemistry> Monosaccharide in which an OH group is replaced with an amino group, often acetylated. Common examples are D galactosamine, D glucosamine, neuraminic acid, muramic acid. Amino sugars are important constituents of bacterial cell walls, some antibiotics, blood group substances, milk oligosaccharides and chitin. (18 Nov 1997) |
| amino sugars | Sugar's in which a hydroxyl group has been replaced with an amino group; e.g., d-glucosamine. (05 Mar 2000) |
| amino- | <prefix> Prefix denoting a compound containing the radical, -NH2. Origin: an(monia) + in(e) + -o- (05 Mar 2000) |
| amino-terminal | <biochemistry> The end of a protein or polypeptide chain with the unattached amino group or the aminoacyl residue containing it. Each amino acid in the chain has an amino group on one side, which is attached to the carboxyl group (COOH group) of the previous amino acid, and a carboxyl group on the other side (which is attached to the amino group of the next amino acid). The other end of the polypeptide chain is called the carboxyl terminal. Synonym: NH2-terminal. (14 Aug 2000) |
| amino-terminal residue | <biochemistry> The only amino acid residue in a polypeptide chain that has a free alpha-amino group, it defines the amino terminus of the polypeptide. (09 Oct 1997) |
| aminoacetic acid | <amino acid, physiology> The simplest amino acid. It is a common residue in proteins, especially collagen and elastin and is not optically active. It is also a major inhibitory neurotransmitter in spinal cord and brainstem of vertebrate central nervous system. (18 Nov 1997) |
| sequence homology, amino acid | The degree of similarity between sequences of amino acids. This information is useful for the understanding of genetic relatedness of certain species. (12 Dec 1998) |
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| N-(5-amino-1-ribosyl-4-imidazolylcarbonyl)-L-aspartic acid 5'-phosphate synthetase | <enzyme> 5-amino-1-ribosyl-4-imidazole carboxylic acid 5'-phosphate (carboxy-air), ATP and aspartate yield n(5-amino-4-imidazolylcarbonyl)-l-aspartic acid 5'-phosphate(succino-aicar), ADP and p Registry number: EC 6.3.4.- (26 Jun 1999) |
| N-(5'-phosphoribosylformimino)-5-amino-1-(5''-phosphoribosyl)-4-imidazolecarboxamide isomerase | <enzyme> Has beta/alpha-barrel fold structure; involved in biosynthesis of histidine Registry number: EC 5.3.1.16 Synonym: hisa gene product, pfacr isomerase, phosphoribosylformimino-5-aminoimidazole carboxamide ribotide isomerase (26 Jun 1999) |
| N(6)-(6-carbamoylhexyl)-FAD-D-amino acid oxidase | <enzyme> A semi-synthetic oxidase; prepared by reacting the succinimido ester of n(6)-(6-carboxyhexyl)-fad with apo-d-amino acid oxidase from pig kidney in the presence of the benzoate Registry number: EC 1.4.3.- Synonym: nch-fad-daao (26 Jun 1999) |
| N-carbamoyl-D-amino acid amidohydrolase | <enzyme> From comamonas sp.e222c; mw 120 kD; hydrolyzes d-enantiomers of various n-carbamoyl-d-amino acids to d-amino acids, ammonia and co2; sensitive to thiol reagents; does not require metal ions Registry number: EC 3.5.1.- Synonym: caa-amidohydrolase, carbamoyl d-aa amidohyrolase (26 Jun 1999) |
| nonessential amino acid | <biochemistry> The amino acid's that can be synthesised by an organism and are thus not required in the diet. (05 Mar 2000) |
| nonpolar amino acid | An alpha-amino acid in which the functional group attached to the alpha-carbon (i.e., R in RCH(NH2)COOH) has hydrophobic properties; e.g., valine, leucine, alpha-aminobutyrate. (05 Mar 2000) |
| succinylalanyl-alanyl-prolyl-phenylalanyl-7-amino-4-methylcoumarin hydrolase | <enzyme> Enzyme may be involved in attainment of transformed state Registry number: EC 3.4.24.- Synonym: suc-ala-ala-pro-phe-amc hydrolase, saapp-amc-hydrolase (26 Jun 1999) |
| D-amino acid malonyltransferase | <enzyme> From mung beans Registry number: EC 2.3.1.- Synonym: 1-aminocyclopropanecarboxylate malonyltransferase, d-acc-malonyltransferase, acc n-malonyltransferase (26 Jun 1999) |
| d-amino-acid oxidase | <enzyme> Chemical name: D-Amino-acid:oxygen oxidoreductase (deaminating) Registry number: EC 1.4.3.3 (12 Dec 1998) |
| D-amino acid transaminase | <enzyme> Catalyses the alpha,beta elimination of the (d)-isomer of beta-chloroalanine or other amino acids to yield pyruvate, chloride and ammonia Registry number: EC 2.6.1.- (26 Jun 1999) |
| D-amino acid transferase | <enzyme> Mw 41 kD; catalyses d-amino acid transfer; d-configuration specific; recognises aromatic d-amino acid esters to form oligo d-amino acid esters Registry number: EC 2.3.2.- (26 Jun 1999) |
| dibasic amino acid | An amino acid containing a second basic group (usually an amino group); e.g., lysine, arginine, ornithine. Synonym: dibasic amino acid. (05 Mar 2000) |
| essential amino acid | <biochemistry> Those amino acids that cannot be synthesised by an organism and must therefore be present in the diet. The term is often applied anthropocentrically to those amino acids required by humans (Ileu, Leu, Lys, Met, Phe, Thr, Try, & Val), though rats need two more (Arg & His). (18 Nov 1997) |
| essential amino acids | Alpha-amino acids nutritionally required by an organism and which must be supplied in its diet (i.e., cannot be synthesised by the organism) either as free amino acid or in proteins. (05 Mar 2000) |