International standards and resources
The Swissprot database ENZYME, an enzyme nomenclature database, describes each type of characterised enzyme for which an Enzyme Commission (EC) number has been provided.
The NC-IUBMB provides information on nomenclature of enzymes.
ExplorEnz (developed at Trinity College Dublin) provides a portal to the data of the IUBMB enzyme nomenclature list.
Enzymes are constantly being discovered and named. To avoid ambiguity, a nomenclature was developed to standardise the names of enzymes. Each enzyme has 3 identifiers: an EC number, a recommended name and a systematic name.
The EC numerical nomenclature classifies enzymes based on reactions, identifying groups of enzymes catalysing similar reactions. Seven categories are recognised:
- EC 1 – oxidoreductases
- EC 2 – transferases
- EC 3 – hydrolases
- EC 4 – lyases
- EC 5 – isomerases
- EC 6 – ligases
- EC 7 – translocases.
Separate EC and the category number with a space. Additional numbers, separated by full stops, further define the reaction type, and specific metabolites and cofactors involved:
EC 3.5.1.2
3 indicates: hydrolase
5 indicates: acting on carbon-nitrogen bonds, other than peptide bonds
1 indicates: in linear amides
2 gives: glutaminase
The recommended name is usually the one that is in common, everyday use; it is usually formed by adding the suffix -ase to the name of the enzyme’s substrate:
EC number: EC 3.5.1.2
Recommended (or accepted) name: glutaminase
A systematic name is used to prevent ambiguity; it provides a brief chemical description of the reaction it catalyses. It is composed of the name of the substate(s) followed by a word ending in -ase that specifies the type of reaction catalysed:
Systematic name: L-glutamine amidohydrolase
Reaction catalysed: L-glutamine + H2O <=> L-glutamate + NH3
Use the recommended common name assigned by the NC-IUBMB. If possible, also use the EC number.
