EC number

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The EC numbers ( Enzyme Commission numbers ) form a numerical classification system for enzymes . Each EC number consists of four numbers separated by dots. Strictly speaking, it is not the enzyme itself that is categorized, but the reaction it catalyzes. It can happen that enzymes that are not related to each other and that catalyze the same reaction are assigned the same EC number.

Enzyme main classes
class designation task Examples Coenzymes
EC  1.-.-.- Oxidoreductases Catalyze redox reactions Dehydrogenases
NAD + , NADP + , FAD , FMN , lipoic acid
EC  2.-.-.- Transferases Catalyze the transfer of a functional group Acyltransferases (contain acetyltransferases )

Phosphotransferases (contain kinases )

S-adenosyl methionine , biotin , cAMP , ATP , thiamine pyrophosphate (TPP), tetrahydrofolic acid
EC  3.-.-.- Hydrolases Catalyze hydrolytic cleavage Amylases


Do not need coenzymes
EC  4.-.-.- Lyases Non-hydrolytic addition or elimination of molecular groups Decarboxylases
TPP, pyridoxal phosphate
EC  5.-.-.- Isomerases Catalyze the intramolecular conversion, e.g. B. Isomerization Racemase
Glucose-1,6-bisphosphate, cobalamin
EC  6.-.-.- Ligases Catalyze the covalent linkage using high-energy cofactors Synthetases
ATP , NAD + , biotin
EC  7.-.-.- Translocases Catalyze the transport of substances to or through cell membranes Ornithine translocase during active transport often adenosine triphosphate (ATP), often also other substances (see membrane transport )

Format of the classification

The classification becomes progressively more specific from left to right. The EC number of the enzyme tripeptide aminopeptidase ( EC ) is composed as follows:

Individual evidence

  1. ^ GP Moss: Recommendations of the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology on the Nomenclature and Classification of Enzymes by the Reactions they Catalyse . International Union of Biochemistry and Molecular Biology . Retrieved December 23, 2010.

Web links