| amino acids, peptides, and proteins | Amino acids and chains of amino acids connected by peptide linkages. (12 Dec 1998) |
|---|---|
| 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) |
| 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 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-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) |
| aromatic d-amino-acid decarboxylase | <enzyme> An enzyme that catalyses the decarboxylation of l-dopa to dopamine, of l-tryptophan to tryptamine, and of l-hydroxytryptophan to serotonin; important in the biosynthetic pathway of catecholamines and melanin. Synonym: dopa decarboxylase, hydroxytryptophan decarboxylase, tryptophan decarboxylase. (05 Mar 2000) |
| aromatic-l-amino-acid decarboxylases | <enzyme> An enzyme group with broad specificity. The enzymes decarboxylate a range of aromatic amino acids including dopa (dopa decarboxylase), tryptophan, and hydroxytryptophan. Chemical name: Aromatic-L-amino-acid carboxy-lyase Registry number: EC 4.1.1.28 (12 Dec 1998) |
| basic 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) |
| receptors, amino acid | Cell surface proteins that bind amino acids and trigger changes which influence the behaviour of cells. Glutamate receptors are the most common receptors for fast excitatory synaptic transmission in the vertebrate central nervous system, and gaba and glycine receptors are the most common receptors for fast inhibition. (12 Dec 1998) |
| glucogenic amino acid | <biochemistry> A type of amino acid with carbon chains that can be broken down into an intermediate of the citric acid cycle such as glycogen and then converted into glucose as a means of entering the normal process of carbohydrate metabolism in the body. Examples include: Glycine, alanine, arginine, and ornithine. (14 Oct 1997) |