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Isomerase

In biochemistry, an isomerase is an enzyme that catalyses the interconversion of polymers. Isomerases thus catalyze reactions of the form

A → B

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Nomenclature

The names of isomerases are formed as "substrate isomerase" (for example, enoyl CoA isomerase), or as "substrate type of isomerase" (for example, phosphoglucomutase).

Classification

Isomerases are classified as EC 5 in the EC number classification of enzymes. Isomerases can be further classified into six subclasses:

EC 5.1 includes enzymes that catalyze racemization (racemases) and epimerization (epimerases)
EC 5.2 includes enzymes that catalyze the isomerization of geometric isomers (cis-trans isomerases)
EC 5.3 includes intramolecular oxidoreductases
EC 5.4 includes intramolecular transferases (mutases)
includes intramolecular lyases
EC 5.99 includes other isomerases (including topoisomerases)

References

EC 5 Introduction from the Department of Chemistry at Queen Mary, University of London

v • d • e Proteins: enzymes
Topics	Active site - Allosteric regulation - Binding site - Catalytically perfect enzyme - Coenzyme - Cofactor - Cooperativity - EC number Enzyme catalysis - Enzyme inhibitor - Enzyme kinetics - Lineweaver-Burk plot - Michaelis-Menten kinetics - List of enzymes
Types	EC1 Oxidoreductases/list - EC2 Transferases/list - EC3 Hydrolases/list - EC4 Lyases/list - EC5 Isomerases/list - EC6 Ligases/list

v • d • e Isomerases: Epimerase and racemases (EC 5.1)
Phenylalanine racemase (ATP-hydrolysing) - Serine racemase - Mandelate racemase - UDP galactose epimerase - Methylmalonyl CoA epimerase

v • d • e Geometric isomerases (EC 5.2)
Cyclophilin - FKBP - Parvulin - Prolyl isomerase

v • d • e Intramolecular oxidoreductases isomerases (EC 5.3)
5.3.1 - Aldoses/Ketoses	Triosephosphate isomerase - Phosphopentose isomerase - Mannose phosphate isomerase - Glucose isomerase
5.3.3 - C=C	Isopentenyl-diphosphate delta isomerase - Enoyl CoA isomerase
5.3.4 - S-S	Protein disulfide isomerase (PDIA3)
5.3.99 - other	Prostaglandin D2 synthase - Prostaglandin E synthase - Prostacyclin synthase - Thromboxane-A synthase

v • d • e Isomerase: mutases (EC 5.4)
5.4.2 Phosphomutases	Phosphoglycerate mutase - Bisphosphoglycerate mutase - Phosphoglucomutase
5.4.99 Other groups	Methylmalonyl-CoA mutase - Lanosterol synthase