The Enzyme Nomenclature (also known as the Enzyme Commission Code) is a species-agnostic controlled vocabulary for specific enzymes and an associated hierarchical classification into 7 main categories.

The Enzyme Nomenclature is maintained by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (IUBMB). A detailed history of the nomenclature since the 1950s can be found here.

There are few notable resources providing access to the Enzyme Nomenclature:

WebsiteHomepageNotes
ExplorEnzhttps://www.enzyme-database.orgThis is the resources officially recommended by IUBMB
IUBMB (via by Queen Mary)https://iubmb.qmul.ac.uk/enzymeThis is a web-based version of the 1992 publication.
IntEnzhttps://www.ebi.ac.uk/intenz
ExPaSyhttps://enzyme.expasy.org

Comment

The Nomenclature Committee website does not yet contain an official policy regarding the use of dashes in the hierarchical categorization of enzymes, so the Bioregistry's regular expression is permissive and accepts both EC identifiers with dashes (e.g. 2.3.-.-) and without dashes (e.g., 2.3). This means you may have to do post-processing of EC identifiers in data integration scenarios.

Prefix
ec
Preferred Prefix
EC
Alternative Prefixes
EC ECCODE eccode EC_CODE intenz ec-code EC number EC-CODE
Keywords
biochemistry centrally registered identifier classification enzyme enzyme commission number enzymology
License
CC-BY-4.0
Links
Homepage
Contact
Kristian Axelsen   0000-0003-3889-2879   kaxelsen
Identifier Space Owner
International Union of Biochemistry and Molecular Biology
Pattern for Local Unique Identifiers

Local identifiers in Enzyme Nomenclature should match this regular expression:
^\d{1,2}(((\.\d{1,3}){1,3})|(\.\d+){2}\.[nB]\d{1,3}|\.-\.-\.-|\.\d{1,3}\.-\.-|\.\d{1,3}\.\d{1,3}\.-)?$

Example Local Unique Identifiers
1.1.1.1   Resolve
2   Resolve
2.3   Resolve
2.3.1   Resolve
2.-.-.-   Resolve
2.3.-.-   Resolve
2.3.1.-   Resolve
2.3.1.n12   Resolve
3.1.26.n2   Resolve
3.4.24.B15   Resolve
Pattern for CURIES

Compact URIs (CURIEs) constructed from Enzyme Nomenclature should match this regular expression:
^EC:\d{1,2}(((\.\d{1,3}){1,3})|(\.\d+){2}\.[nB]\d{1,3}|\.-\.-\.-|\.\d{1,3}\.-\.-|\.\d{1,3}\.\d{1,3}\.-)?$

Example CURIEs
EC:1.1.1.1
EC:2
EC:2.3
EC:2.3.1
EC:2.-.-.-
EC:2.3.-.-
EC:2.3.1.-
EC:2.3.1.n12
EC:3.1.26.n2
EC:3.4.24.B15
Publications
2000 The ENZYME database in 2000
References
GitHub Issue https://github.com/biopragmatics/bioregistry/issues/681
Ontology

A summary of the relations in the Bioregistry schema can be found here.

Provided By
brenda kegg.enzyme sabiork.ec
Metaregistry Enzyme Nomenclature

The metaregistry provides mappings between the Bioregistry and other registries. There are 14 mappings to external registries for this resource with 11 unique external prefixes.

Registry Name Registry Metaprefix External Prefix Curate
BARTOC Basic Register of Thesauri, Ontologies & Classifications logo bartoc 671
BioContext biocontext EC-CODE
EDAM EDAM Ontology logo edam 1011
FAIRSharing FAIRSharing logo fairsharing FAIRsharing.rfLD2u
GO Gene Ontology Registry logo go EC
Integbio Integbio logo integbio nbdc00508
Identifiers.org Identifiers.org logo miriam ec-code
N2T Name-to-Thing logo n2t ec-code
Pathguide Pathguide logo pathguide 106
Prefix Commons Prefix Commons logo prefixcommons intenz
re3data Registry of Research Data Repositories logo re3data r3d100010803
TogoID togoid Ec
UniProt UniProt Cross-ref database logo uniprot DB-0024
Wikidata Wikidata Property logo wikidata P591
Providers

A provider turns a local unique identifiers from a resource into a URI. Many providers are also resolvable as URLs (i.e., they can be used in a web browser).

The local unique identifier 1.1.1.1 is used to demonstrate the providers available for Enzyme Nomenclature. A guide for curating additional providers can be found here.

Name Metaprefix URI
Enzyme Nomenclature ec https://www.ebi.ac.uk/intenz/query?cmd=SearchEC&ec=1.1.1.1
Bioregistry bioregistry https://bioregistry.io/ec:1.1.1.1
Identifiers.org miriam https://identifiers.org/ec-code:1.1.1.1
Name-to-Thing n2t https://n2t.net/ec-code:1.1.1.1
Extra Providers

Additional providers curated in the Bioregistry are listed here. These are typically inherited from Identifiers.org or Prefix Commons, and need extra curation.

Code Name URL
bio2rdf Bio2RDF http://bio2rdf.org/intenz:1.1.1.1
expasy Enzyme nomenclature database, ExPASy (Expert Protein Analysis System) https://enzyme.expasy.org/EC/1.1.1.1
expenz ExploreEnz at Trinity College http://www.enzyme-database.org/query.php?ec=1.1.1.1