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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

Additional recommended knowledge

Daily Sensitivity Test

Essential Laboratory Skills Guide

How to quickly check pipettes?

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