The glutamine molecule - rotatable in 3 dimensions
3 letter code: gln
1 letter code: Q
Glutamine is an amino acid containing an amide group. It is effectively glutamic acid with the -OH group on its acidic side chain replaced by a an extra amino group.
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-CO-NH2, an ethyl group with an amide group attached. An amide group is a carbonyl group (-C=O) - grey, with red - attached to another amino group - blue with 2 whites - at the other end of the molecule. This extra amino group gives it extra basic characteristics: the amino group can ionise and interact with other R groups within a polypeptide chain. This is independent of the other amino group which is used to form covalent peptide links in a protein.