ec

is a Ontology.

The Enzyme Commission classification system provides a hierarchical numbering scheme for enzymes based on the chemical reactions they catalyze, maintained by the IUBMB.

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chemistry and biochemistry, enzymes

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CC0 1.0

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ec

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Product Summary

Products

From this Resource
ID Name URL Category Format Description
ec.database Enzyme Commission Official Database www.enzyme-database.org Graphical Interface http Official Enzyme Commission nomenclatu...
From other Resources
ID Name URL Category Format Relation Description
kg-microbe.graph.raw KG-Microbe KGX Graph - Raw latest Graph kgx had primary source Raw source files for all KG-Microbe f...
kg-microbe.graph.core KG-Microbe KGX Graph - Core latest Graph kgx had primary source The core KG KG-Microbe-Core with onto...
kg-microbe.graph.biomedical KG-Microbe KGX Graph - Biomedical latest Graph kgx had primary source Core plus human biomedical data (onto...
kg-microbe.graph.function KG-Microbe KGX Graph - Function latest Graph kgx had primary source Core plus Uniprot genome annotations
kg-microbe.graph.biomedical-function KG-Microbe KGX Graph - Biomedical-Function KGMicrobe-biomedical-function-20250222.tar.gz (4.3 GB) Graph kgx had primary source Biomedical plus Uniprot genome annota...
obo-db-ingest.ec.tsv ec Nodes TSV ec.tsv (276.6 KB) Product tsv had primary source ec Nodes TSV
obo-db-ingest.ec.obo ec OBO ec.obo (2.8 MB) Product obo had primary source ec OBO
obo-db-ingest.ec.owl ec OWL ec.owl (3.2 MB) Product owl had primary source ec OWL
obo-db-ingest.ec.json ec OBO Graph JSON ec.json (1.7 MB) Product json had primary source ec OBO Graph JSON
obo-db-ingest.ec.sssom.tsv ec SSSOM ec.sssom.tsv (8.5 KB) Mapping sssom had primary source ec SSSOM
spoke.graph SPOKE Graph data-tools Graph http had primary source The SPOKE knowledge graph containing ...

Details

Enzyme Commission

Overview

The Enzyme Commission (EC) classification system is a hierarchical numerical classification scheme for enzymes based on the chemical reactions they catalyze. Maintained by the International Union of Biochemistry and Molecular Biology (IUBMB), EC numbers provide a standardized nomenclature used universally in biochemistry and molecular biology.

Classification Structure

EC numbers consist of four hierarchical levels:

  1. First digit: Main enzyme class (1-7)
    • EC 1: Oxidoreductases
    • EC 2: Transferases
    • EC 3: Hydrolases
    • EC 4: Lyases
    • EC 5: Isomerases
    • EC 6: Ligases
    • EC 7: Translocases
  2. Second digit: Subclass (type of substrate or chemical group)
  3. Third digit: Sub-subclass (further specificity)
  4. Fourth digit: Serial number (specific enzyme)

Example: EC 3.2.1.1 represents α-amylase (a hydrolase acting on glycosidic bonds)

Key Features

  • Hierarchical Classification: Organized by reaction type and substrate specificity
  • Universal Standard: Widely adopted across biological databases and publications
  • Systematic Naming: Each enzyme receives a unique EC number and systematic name
  • Reaction Specificity: Classification based on catalyzed reaction, not protein structure
  • Regular Updates: Continuously maintained with new enzyme discoveries

Applications

  • Functional Annotation: Classifying gene products by enzymatic function
  • Metabolic Pathway Analysis: Mapping enzymes to biochemical pathways
  • Comparative Genomics: Analyzing enzyme distributions across organisms
  • Drug Discovery: Identifying enzyme targets for therapeutic intervention
  • Systems Biology: Integrating enzymatic functions in metabolic models

Integration

EC classifications are integrated into numerous biological databases including:

  • UniProt (protein functional annotations)
  • KEGG (metabolic pathway mapping)
  • BRENDA (enzyme information)
  • Rhea (biochemical reactions)
  • KG-Microbe (microbial functional genomics)

Data Access

EC numbers and enzyme information are freely available through:

  • IUBMB Enzyme Nomenclature Committee: https://www.enzyme-database.org/
  • ExPASy Enzyme Database: https://enzyme.expasy.org/
  • BRENDA Enzyme Database: https://www.brenda-enzymes.org/

For more information about how EC classifications are used in knowledge graphs, see the KG-Microbe project.

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Created: November 25, 2025 | Last modified: September 23, 2026