- EC number
: "This article is about the Enzyme Commission codes. For the European Commission system for coding chemicals, see
The Enzyme Commission number (EC number) is a numerical classification scheme for
enzymes, based on the chemical reactions they catalyze.As a system of enzyme nomenclature, every EC number is associated with a recommended name for the respective enzyme.
Strictly speaking, EC numbers do not specify enzymes, but enzyme-catalyzed reactions. If different enzymes (for instance from different organisms) catalyze the same reaction, then they receive the same EC number. By contrast,
UniProtidentifiers uniquely specify a protein by its amino acid sequence. [cite web
publisher = ExPASy
title = ENZYME (Enzyme nomenclature database)
url = http://www.expasy.org/enzyme/
accessdate = 2006-03-14]
Format of number
Every enzyme code consists of the letters "EC" followed by four numbers separated by periods. Those numbers represent a progressively finer classification of the enzyme.
For example, the
tripeptide aminopeptidases have the code "EC 126.96.36.199", whose components indicate the following groups of enzymes:
* "EC 3" enzymes are
hydrolases (enzymes that use waterto break up some other molecule)
* "EC 3.4" are hydrolases that act on
* "EC 3.4.11" are those hydrolases that cleave off the amino-terminal
amino acidfrom a polypeptide
* "EC 188.8.131.52" are those that cleave off the amino-terminal end from a
Top level codes
The enzyme nomenclature scheme was developed starting in
1955, when the International Congress of Biochemistry in Brusselsset up an Enzyme Commission.
The first version was published in
The current sixth edition, published by the
International Union of Biochemistry and Molecular Biologyin 1992, contains 3196 different enzymes.
TC number(classification of membrane transport proteins)
List of enzymes
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