Mutase is an enzyme, which belongs to the isomerase class. This family of enzymes is responsible for speeding up the movement of a functional group from one part of a molecule to another. In basic terms, mutases facilitate and catalyse group transfers within the same molecule. Mutase is most commonly discussed when talking about the transfer of phosphate from one group to another.
The most well-known example of mutase enzymes is phosphoglycerate mutase, also known as PGM.
Phosphoglycerate mutase (PGM) is involved in step 8 of the glycolysis process. These enzymes catalyse the movement of a phosphate group from C-3 to C-2, contributing to the conversion of 3PG (3-phosphoglycerate) to 2PG (2-phosphoglycerate). This is done through a 2-3-biphosphoglycerate go-between. PGM enzymes are classified according to two categories and are either cofactor dependent (dPGM) or cofactor independent (iPGM). The cofactor-dependent dPGM enzyme comprises 250 amino acids, and can be found in all vertebrates in addition to some forms of bacteria, fungi and invertebrates.
Mutase Function and mechanism
PGM is an isomerase enzyme, which performs the function of transferring a phosphate group from C3 to C2. There are 3 reactions that can be catalysed by cofactor-dependent PGMs: these include: Mutase reactions that convert 3PG to 2PG and mutase reactions that convert 2PG to 3PG, Phosphatase reactions that produce phosphoglycerate from 2,3-bisphosphoglycerate, Synthase reactions that create 2,3-bisphosphoglycerate from 1,3-bisphosphoglycerate
Phosphoglycerate mutase produces reversible reactions.
The secondary structure of PGM is categorised as an alpha/beta protein, which has three alpha, beta, alpha layers. Phosphoglycerate mutase comprises a mixed beta structure made from six strands. Strand 5 is positioned as an anti-parallel to the others. The quaternary structure has two identical components, and as such, the enzyme is known as a homodimer. Although the active site of the quaternary structure is similar, there are variations called isozymes, which differ according to the kind of tissue targeted by the enzyme.