<p>The <strong>Enzyme Commission number</strong> (<strong>EC number</strong>) is a numerical classification scheme for <font color="#810081">enzymes</font>, based on the chemical reactions they catalyze. As a system of <strong>enzyme nomenclature</strong>, every EC number is associated with a recommended name for the respective enzyme.</p>

<p>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, UniProt identifiers uniquely specify a protein by its amino acid sequence.<sup class="reference" id="_ref-0">[1]</sup></p>

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<h2><span class="mw-headline">Format of number</span></h2>