In consultation with the IUPAC-IUBMB Joint Commission on Biochemical Nomenclature (JCBN)
World Wide Web version prepared byG.P. Moss
School of Physical and Chemical Sciences, Queen Mary University of London,
Mile End Road, London, E1 4NS, UK
g.p.moss@qmul.ac.uk
This page contains general information on enzyme nomenclature. It includes links to individual documents, and the number of these will increase as more sections of the enzyme list are revised.Links to other relevant databases are provided. It also providesadvice on how to suggest new enzymes for listing, or correction of existing entries. There is a list ofabbreviations used in the database.
Historical Introduction
InEnzyme Nomenclature 1992 there was anhistorical introduction. This web version is slightly edited from that in the book.
Printed Version
Published inEnzyme Nomenclature 1992[Academic Press, San Diego, California, ISBN 0-12-227164-5 (hardback), 0-12-227165-3 (paperback)] withSupplement 1 (1993),Supplement 2 (1994),Supplement 3 (1995),Supplement 4 (1997) andSupplement 5 (inEur. J. Biochem. 1994,223, 1-5;Eur. J. Biochem. 1995,232, 1-6;Eur. J. Biochem. 1996,237, 1-5;Eur. J. Biochem. 1997,250; 1-6, andEur. J. Biochem. 1999,264, 610-650; respectively) [Copyright IUBMB].
Each enzyme has recorded at the end details of when first published in Enzyme Nomenclature or when added to the database and its subsequenthistory.
Web Version of Enzyme Nomenclature
The complete contents ofEnzyme Nomenclature, 1992 (plus subsequentsupplements and other changes) are listed below in enzyme number order giving just therecommended name. Each entry provides a link to details of that enzyme. Alternatively if looking for a specific reaction used in the classification of enzymes the broad outline defined by the first two numbers are given below. Each of thesesubclass entries is linked to a location where the category is subdivided to sub-subclasses. These in turn are linked to a list of recommended names for each enzyme in the sub-subclass.
List of Recommended Names for Enzymes
The common names of all listed enzymes are listed below, along with their EC numbers. Where an enzyme has been deleted or transferred to another EC number, this information is also indicated. Each list is linked to eitherseparate entries for each entry or to files withup to 50 enzymes in each file.
Proposed additions and changes to this list are given separately (details below).
Common Names for: List linked to: EC 1.1 to EC 1.3 separate up to 50 EC 1.4 to EC 1.97 separate up to 50 EC 2.1 to EC 2.4.1 separate up to 50 EC 2.4.2 to EC 2.9 separate up to 50 EC 3.1 to EC 3.3 separate up to 50 EC 3.4 to EC 3.12 separate up to 50 EC 4 separate up to 50 EC 5 separate up to 50 EC 6 separate up to 50 EC 7 separate up to 50
Glossary, Reaction pathways and Links to Other Databases
A start has been made in showing the pathways in whichenzymes participate. Thus, for example, a link underEC 5.3.3.2 (isopentenyl-diphosphate isomerase) leads to the pathway from mevalonate to terpenes, and links underEC 1.14.99.7 (squalene monooxygenase) andEC 5.4.99.7 (lanosterol synthase) lead to pathways of steroid formation. For other enzymes a glossary entry has been added which may be just a systematic name or a link to agraphic representation. Theglossary fromEnzyme Nomenclature, 1992 may also be consulted. This has been updated with subsequent glossary entries. Each enzyme entry has links to other databases. For recent entries these may not yet have been implemented on the other datebase. For details on the information providedclick here.
Enzyme Supplement 6 to 24 (electronic only)
Six documents listing additions and corrections to previous entries were approved in 2000. These together formSupplement 6.
Five documents were approved in 2001 and formSupplement 7.
Three documents (six files) were approved in 2002 and formSupplement 8.
Three documents (five files) were approved in 2003 and formSupplement 9.
Three documents were approved in 2004 and formSupplement 10.
Six documents were approved in 2005 and formSupplement 11.
Four files were approved in 2006 and formSupplement 12.
Two files were approved in 2007 and formSupplement 13.
Eleven files were approved in 2008 and formSupplement 14.
Seven files were approved in 2009 and formSupplement 15.
Seven files were approved in 2010 and formSupplement 16.
Eight files were approved in 2011 and formSupplement 17.
Five files were approved in 2012 and formSupplement 18.
Three files were approved in 2013 and formSupplement 19.
Four files were approved in 2014 and formSupplement 20.
Three files were approved in 2015 and formSupplement 21.
Four files were approved in 2016 and formSupplement 22.
Four files were approved in 2017 and formSupplement 23.
Five files has been approved in 2018 and formSupplement 24.
Four files has been approved in 2019 and formSupplement 25.
Four files has been approved in 2020 and formSupplement 26.
Three files has been approved in 2021 and formSupplement 27.
Four files has been approved in 2022 and formSupplement 28.
Two files has been approved in 2023 and formSupplement 29.
Three files has been approved in 2024 and formSupplement 30.
One files has been approved in 2025 and formSupplement 31.
The entries are© Copyright to the International Union of Biochemistry and Molecular Biology.
Proposed New Entries and Revised Entries
Proposals for new entries to the Enzyme List and revisions of previously published entries are available from the following file:
New Enzymes (last batch addedOctober 2025)Suggestions and comments should be made toDr Andrew McDonald (Department of Biochemistry, Trinity College Dublin, Dublin 2, Ireland)
Criteria for inclusion
Before an enzyme can be included in the list direct experimental evidence is required that the proposed enzyme actually catalyses the reaction claimed. Close sequence similarity is not sufficient without evidence for the reaction catalysed, because only a small change in sequence is sufficient to change the activity or specificity of an enzyme. Furthermore, because classification is based solely on the reaction catalysed, there are cases where proteins of very different sequencescatalyse the same reaction. The existence of an apparent gap in a biochemical pathway, are not, in themselves, sufficient for classification purposes.
How to suggest new entries and correct existing entries
Information aboutnew enzymes orcorrections to existing entries may be reported directly from these web pages or by using the form printed in the back ofEnzyme Nomenclature.Advice is available on how to suggest new enzymes for listing, or corrections of existing entries. Comments and suggestions on enzyme classification and nomenclature also may be sent toDr Andrew McDonald (Department of Biochemistry, Trinity College Dublin, Dublin 2, Ireland)
Rules for the Classification and Nomenclature of Enzymes
InEnzyme Nomenclature 1992 there was a section on general principles; recommended and systematic names; scheme of classification and numbering of enzymes; and rules for classification and nomenclature. Thisweb version is slightly edited from that in the book.
The links are to a list ofsub-subclasses which in turn list the enzymes linked to separate files for each enzyme,or to a list as part of a file withup to 50 enzymes per file.
| 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 the reaction X-H + Y-H = X-Y | 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 |
| EC 7 | Translocases | ||
| EC 7.1 | Catalysing the translocation of hydrons | sub-subclasses | up to 50 |
| EC 7.2 | Catalysing the translocation of inorganic cations | sub-subclasses | up to 50 |
| EC 7.3 | Catalysing the translocation of inorganic anions and their chelates | sub-subclasses | up to 50 |
| EC 7.4 | Catalysing the translocation of amino acids and peptides | sub-subclasses | up to 50 |
| EC 7.5 | Catalysing the translocation of carbohydrates and their derivatives | sub-subclasses | up to 50 |
| EC 7.6 | Catalysing the translocation of other compounds | sub-subclasses | up to 50 |
Return to mainIUBMB Biochemical Nomenclature home page