EC number

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 Hydrogenases Oxidases Oxygenases Hydroxylases	NAD ⁺ , NADP ⁺ , FAD , FMN , lipoic acid
EC 2.-.-.-	Transferases	Catalyze the transfer of a functional group	Acyltransferases (contain acetyltransferases ) aminotransferases Phosphotransferases (contain kinases )	S-adenosyl methionine , biotin , cAMP , ATP , thiamine pyrophosphate (TPP), tetrahydrofolic acid
EC 3.-.-.-	Hydrolases	Catalyze hydrolytic cleavage	Amylases Esterases Lipases Phosphatases Peptidases	Do not need coenzymes
EC 4.-.-.-	Lyases	Non-hydrolytic addition or elimination of molecular groups	Decarboxylases aldolases synthases	TPP, pyridoxal phosphate
EC 5.-.-.-	Isomerases	Catalyze the intramolecular conversion, e.g. B. Isomerization	Racemase Mutases	Glucose-1,6-bisphosphate, cobalamin
EC 6.-.-.-	Ligases	Catalyze the covalent linkage using high-energy cofactors	Synthetases carboxylases	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 3.4.11.4 ) is composed as follows:

EC 3.-.-.- : hydrolase
EC 3.4.-.- : peptidase ( hydrolysis of a peptide bond )
EC 3.4.11.- : aminopeptidase
EC 3.4.11.4 : tripeptide aminopeptidase (catalyzes the cleavage of an amino-terminal amino acid from a tripeptide )

Individual evidence

^ 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

ExplorEnz - database of the of the IUBMB Enzyme Nomenclature List. Andrew McDonald (School of Biochemistry & Immunology, Trinity College, Dublin 2, Ireland), accessed February 12, 2016 .

[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.