Enzyme Nomenclature

Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (NC-IUBMB)

Table 1: 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

Subclass	Name	Enzyme file type
EC 1	Oxidoreductases
EC 1.1	Acting on the CH-OH group of donors	sub-subclasses	up to 50
EC 1.2	Acting on the aldehyde or oxo group of donors	sub-subclasses	up to 50
EC 1.3	Acting on the CH-CH group of donors	sub-subclasses	up to 50
EC 1.4	Acting on the CH-NH₂ group of donors	sub-subclasses	up to 50
EC 1.5	Acting on the CH-NH group of donors	sub-subclasses	up to 50
EC 1.6	Acting on NADH or NADPH	sub-subclasses	up to 50
EC 1.7	Acting on other nitrogenous compounds as donors	sub-subclasses	up to 50
EC 1.8	Acting on a sulfur group of donors	sub-subclasses	up to 50
EC 1.9	Acting on a heme group of donors	sub-subclasses	up to 50
EC 1.10	Acting on diphenols and related substances as donors	sub-subclasses	up to 50
EC 1.11	Acting on a peroxide as acceptor	sub-subclasses	up to 50
EC 1.12	Acting on hydrogen as donor	sub-subclasses	up to 50
EC 1.13	Acting on single donors with incorporation of molecular oxygen (oxygenases)	sub-subclasses	up to 50
EC 1.14	Acting on paired donors, with incorporation or reduction of molecular oxygen	sub-subclasses	up to 50
EC 1.15	Acting on superoxide radicals as acceptor	sub-subclasses	up to 50
EC 1.16	Oxidising metal ions	sub-subclasses	up to 50
EC 1.17	Acting on CH or CH₂ groups	sub-subclasses	up to 50
EC 1.18	Acting on iron-sulfur proteins as donors	sub-subclasses	up to 50
EC 1.19	Acting on reduced flavodoxin as donor	sub-subclasses	up to 50
EC 1.20	Acting on phosphorus or arsenic in donors	sub-subclasses	up to 50
EC 1.21	Acting on X-H and Y-H to form an X-Y bond	sub-subclasses	up to 50
EC 1.22	Acting on halogen in donors	sub-subclasses	up to 50
EC 1.23	Reducing C-O-C group as acceptor	sub-subclasses	up to 50
EC 1.97	Other oxidoreductases	sub-subclasses	up to 50
EC 2	Transferases
EC 2.1	Transferring one-carbon groups	sub-subclasses	up to 50
EC 2.2	Transferring aldehyde or ketonic groups	sub-subclasses	up to 50
EC 2.3	Acyltransferases	sub-subclasses	up to 50
EC 2.4	Glycosyltransferases	sub-subclasses	up to 50
EC 2.5	Transferring alkyl or aryl groups, other than methyl groups	sub-subclasses	up to 50
EC 2.6	Transferring nitrogenous groups	sub-subclasses	up to 50
EC 2.7	Transferring phosphorus-containing groups	sub-subclasses	up to 50
EC 2.8	Transferring sulfur-containing groups	sub-subclasses	up to 50
EC 2.9	Transferring selenium-containing groups	sub-subclasses	up to 50
EC 2.10	Transferring molybdenum- or tungsten-containing groups	sub-subclasses	up to 50
EC 3	Hydrolases
EC 3.1	Acting on ester bonds	sub-subclasses	up to 50
EC 3.2	Glycosylases	sub-subclasses	up to 50
EC 3.3	Acting on ether bonds	sub-subclasses	up to 50
EC 3.4	Acting on peptide bonds (peptidases)	sub-subclasses	up to 50
EC 3.5	Acting on carbon-nitrogen bonds, other than peptide bonds	sub-subclasses	up to 50
EC 3.6	Acting on acid anhydrides	sub-subclasses	up to 50
EC 3.7	Acting on carbon-carbon bonds	sub-subclasses	up to 50
EC 3.8	Acting on halide bonds	sub-subclasses	up to 50
EC 3.9	Acting on phosphorus-nitrogen bonds	sub-subclasses	up to 50
EC 3.10	Acting on sulfur-nitrogen bonds	sub-subclasses	up to 50
EC 3.11	Acting on carbon-phosphorus bonds	sub-subclasses	up to 50
EC 3.12	Acting on sulfur-sulfur bonds	sub-subclasses	up to 50
EC 3.13	Acting on carbon-sulfur bonds	sub-subclasses	up to 50
EC 4	Lyases
EC 4.1	Carbon-carbon lyases	sub-subclasses	up to 50
EC 4.2	Carbon-oxygen lyases	sub-subclasses	up to 50
EC 4.3	Carbon-nitrogen lyases	sub-subclasses	up to 50
EC 4.4	Carbon-sulfur lyases	sub-subclasses	up to 50
EC 4.5	Carbon-halide lyases	sub-subclasses	up to 50
EC 4.6	Phosphorus-oxygen lyases	sub-subclasses	up to 50
EC 4.7	Carbon-phosphorus lyases	sub-subclasses	up to 50
EC 4.99	Other lyases	sub-subclasses	up to 50
EC 5	Isomerases
EC 5.1	Racemases and epimerases	sub-subclasses	up to 50
EC 5.2	cis-trans-Isomerases	sub-subclasses	up to 50
EC 5.3	Intramolecular isomerases	sub-subclasses	up to 50
EC 5.4	Intramolecular transferases (mutases)	sub-subclasses	up to 50
EC 5.5	Intramolecular lyases	sub-subclasses	up to 50
EC 5.99	Other isomerases	sub-subclasses	up to 50
EC 6	Ligases
EC 6.1	Forming carbon—oxygen bonds	sub-subclasses	up to 50
EC 6.2	Forming carbon—sulfur bonds	sub-subclasses	up to 50
EC 6.3	Forming carbon—nitrogen bonds	sub-subclasses	up to 50
EC 6.4	Forming carbon—carbon bonds	sub-subclasses	up to 50
EC 6.5	Forming phosphoric ester bonds	sub-subclasses	up to 50
EC 6.6	Forming nitrogen—metal bonds	sub-subclasses	up to 50