Isoglutamine or α-glutamine is an amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

 which is derived from glutamic acid

Glutamic acid

Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...

 by substituting the carboxyl group in position 1 with an amide

Amide

In chemistry, an amide is an organic compound that contains the functional group consisting of a carbonyl group linked to a nitrogen atom . The term refers both to a class of compounds and a functional group within those compounds. The term amide also refers to deprotonated form of ammonia or an...

 group. This is in contrast to the proteinogenic amino acid glutamine

Glutamine

Glutamine is one of the 20 amino acids encoded by the standard genetic code. It is not recognized as an essential amino acid but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders...

, which is the 5-amide of glutamic acid.

Isoglutamine can form the C-terminus of a peptide chain, as in muramyl dipeptide

Muramyl dipeptide

Muramyl dipeptide is a peptidoglycan constituent of both Gram positive and Gram negative bacteria. It is composed of N-acetylmuramic acid linked by its lactic acid moiety to the N-terminus of an L-alanine D-isoglutamine dipeptide.-See also:* Dipeptide...

 (MDP), a constituent of bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

l cell wall

Cell wall

The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...

s. It can also occur inside a peptide chain, in which case the chain is continued at the carboxyl group and isoglutamine behaves as a γ-amino acid, as in mifamurtide

Mifamurtide

Mifamurtide is a drug against osteosarcoma, a kind of bone cancer mainly affecting children and young adults, which is lethal in about a third of cases. The drug was approved in Europe in March 2009.- History :...

, a synthetic derivative of MDP used to treat osteosarcoma

Osteosarcoma

Osteosarcoma is an aggressive cancerous neoplasm arising from primitive transformed cells of mesenchymal origin that exhibit osteoblastic differentiation and produce malignant osteoid...

.

Stereochemistry

Substituting L-glutamic acid, the proteinogenic enantiomer

Enantiomer

In chemistry, an enantiomer is one of two stereoisomers that are mirror images of each other that are non-superposable , much as one's left and right hands are the same except for opposite orientation. It can be clearly understood if you try to place your hands one over the other without...

, gives L-isoglutamine, which has S configuration. D-Isoglutamine, the derivative of the non-proteinogenic D-glutamic acid, has R configuration. The latter is the form occurring in MDP and mifamurtide.