Amino acid symbols: Symbols that stand for the amino acids, the building blocks of protein. Each amino acid has both a three-letter symbol and a single-letter symbol. For example, the three-letter and single-letter symbols for alanine are Ala and A. The three-letter symbols (such as Ala) are much more widely used than the single letter ones (such as A).
Therefore, the following list is limited to the three-letter symbols and is further limited to those 20 alpha-amino acids specified by the genetic code:
Aspartic acid: Asp
Glutamic acid: Glu
These three-letter symbols for amino acids are used not only to refer to an individual amino acid but also to present the amino acid sequence of a polypeptide or a protein. For example, part of the sequence of insulin reads: Gly-Ile-Val-Glu-Gln-Cys-Cys-Ala-Ser-Val. The N-terminal residue of the polypeptide or protein is by convention always on the left and the sequence reads from left-to-right toward the C-terminal residue of the polypeptide or protein.
- Amino acid, branched-chain
Amino acid, branched-chain: One of the amino acids that has a branch chain, namely, Leucine, isoleucine, and valine.
- Amino acid, essential
Amino acid, essential: An amino acid that cannot be made by humans and so is essential to the human diet. There are 9 essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
- Amino acid, nonessential
Amino acid, nonessential: An amino acid that can be made by humans and so is not essential to the human diet. There are 11 nonessential amino acids: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.
Aminotransferase: An enzyme that catalyzes the transfer of an amino group from a donor molecule to a recipient molecule. The donor molecule is usually an amino acid and the recipient molecule is usually an alpha-2 keto acid. Two of the best-known enzymes in this class are serum glutamic oxaloacetic transaminase (SGOT) and serum glutamic pyruvic […]
Amitriptyline: An antidepressant medication. In some patients with depression, abnormal levels of brain chemicals called neurotransmitters may relate to the depression. Amitriptyline elevates mood by raising the level of neurotransmitters in brain tissue. Amitriptyline is also a sedative that is useful for depressed patients with insomnia, restlessness, and nervousness. It is sometimes used to treat […]