Isomerase
Encyclopedia
In biochemistry
, an isomerase is an enzyme
that catalyzes the structural rearrangement of isomer
s. Isomerases thus catalyze reactions of the form
where B is an isomer of A.
), or as "substrate type of isomerase" (for example, phosphoglucomutase
).
classification of enzymes: EC 5. Isomerases can be further classified into six subclasses:
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...
, an isomerase is an enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
that catalyzes the structural rearrangement of isomer
Isomer
In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...
s. Isomerases thus catalyze reactions of the form
- A → B
where B is an isomer of A.
Nomenclature
The names of isomerases are formed as "substrate isomerase" (for example, enoyl CoA isomeraseEnoyl CoA isomerase
Enoyl CoA isomerase or dodecenoyl-coenzyme A delta-isomerase is an enzyme that catalyzes conversion of cis-double bonds of fatty acids at position 3 to trans double bonds at position 2. It has a special importance in metabolism of unsaturated fatty acids.-External links:...
), or as "substrate type of isomerase" (for example, phosphoglucomutase
Phosphoglucomutase
Phosphoglucomutase is an enzyme that transfers a phosphate group on an α-D-glucose monomer from the 1' to the 6' position in the forward direction or the 6' to the 1' position in the reverse direction....
).
Classification
Isomerases have their own ECEC number
The Enzyme Commission number is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze....
classification of enzymes: EC 5. Isomerases can be further classified into six subclasses:
- EC 5.1 includes enzymes that catalyze racemizationRacemizationIn chemistry, racemization refers to the converting of an enantiomerically pure mixture into a mixture where more than one of the enantiomers are present...
(racemases) and epimerEpimerIn chemistry, epimers are diastereomers that differ in configuration of only one stereogenic center. Diastereomers are a class of stereoisomers that are non-superposable, non-mirror images of one another....
ization (epimerases) - EC 5.2 includes enzymes that catalyze the isomerization of geometric isomersGeometric isomerismIn organic chemistry, cis/trans isomerism or geometric isomerism or configuration isomerism or E/Z isomerism is a form of stereoisomerism describing the orientation of functional groups within a molecule...
(cis-trans isomeraseCis-trans isomeraseCis-trans isomerase is a type of isomerase which catalyzes the isomerization of geometric isomers.Examples include photoisomerase and immunophilins such as cyclophilin....
s) - EC 5.3 includes intramolecularIntramolecularIntramolecular in chemistry describes a process or characteristic limited within the structure of a single molecule, a property or phenomenon limited to the extent of a single molecule.- Examples :...
oxidoreductaseOxidoreductaseIn biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule to another...
s - EC 5.4 includes intramolecular transferaseTransferaseIn biochemistry, a transferase is an enzyme that catalyzes the transfer of a functional group from one molecule to another . For example, an enzyme that catalyzed this reaction would be a transferase:In this example, A would be the donor, and B would be the acceptor...
s (mutaseMutaseA mutase is an enzyme that catalyzes the shifting of a functional group from one position to another within the same molecule. Examples of this are bisphosphoglycerate mutase, which appears in red blood cells and phosphoglycerate mutase, which acts in glycolysis. In glycolysis, it changes...
s) - EC 5.5 includes intramolecular lyaseLyaseIn biochemistry, a lyase is an enzyme that catalyzes the breaking of various chemical bonds by means other than hydrolysis and oxidation, often forming a new double bond or a new ring structure...
s - EC 5.99 includes other isomerases (including topoisomeraseTopoisomeraseTopoisomerases are enzymes that regulate the overwinding or underwinding of DNA. The winding problem of DNA arises due to the intertwined nature of its double helical structure. For example, during DNA replication, DNA becomes overwound ahead of a replication fork...
s)