The glutamic acid molecule - rotatable in 3 dimensions
3 letter code: glu
1 letter code: E
Glutamic acid is an amino acid containing an extra carboxylic acid group on its side-chain. It may also be described as 2-aminopentanedioic acid.
Like all amino acids, it has an amino group (-NH2) - blue with 2 white balls - at one end, and a carboxylic acid group (-COOH) - grey, connected to red, and red and white - at the other end. These groups are used to link onto other amino acids by peptide bonds. Between these is the
α- (alpha) carbon to which the 'R' group is attached.
Its 'R' group is -(CH2)2-COOH, an ethyl group with anothercarboxylic acid group (-COOH) attached - grey, with red and red and white - at the other end of the molecule. This extra carboxylic acid group gives it extra acidic characteristics: the acid group can ionise and interact with other R groups within a polypeptide chain. This is independent of the other acid group which is used to form covalent peptide links in a protein.
The sodium salt of glutamic acid is called monosodium glutamate (MSG). It is well known in chinese cookery and as a flavour enhancer in snack foods. In digestion, glutamic acid is produced "naturally" when many proteins are hydrolysed. The monosodium part of the name refers to the fact that only one of the carboxylic acids (the one described here as bonding acid) is
and a sodium ion (Na+) is also present.