Lyase

<h2 id="nomenclature">Nomenclature</h2>
<p>Systematic names are formed as "<i>substrate group-lyase</i>." Common names include <a href="/facts/Decarboxylase/Vfnl4VWe">decarboxylase</a>, <a href="/facts/Dehydratase/xTTCsWP2">dehydratase</a>, <a href="/facts/Aldolase/jBS69B6G">aldolase</a>, etc. When the product is more important, <a href="/facts/Synthase/39C9l6fN">synthase</a> may be used in the name, e.g. phosphosulfolactate synthase (EC 4.4.1.19, Michael addition of sulfite to phosphoenolpyruvate).
A combination of both an elimination and a Michael addition is seen in O-succinylhomoserine (thiol)-lyase (MetY or MetZ) which catalyses first the γ-elimination of O-succinylhomoserine (with succinate as a leaving group) and then the addition of sulfide to the vinyl intermediate, this reaction was first classified as a lyase (EC 4.2.99.9), but was then reclassified as a transferase (EC 2.5.1.48).
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<h2 id="classification">Classification</h2>
<p>Lyases are classified as EC 4 in the <a href="/facts/Enzyme_Commission_number/Y5GNLRKX">EC number</a> classification of enzymes. Lyases can be further classified into seven subclasses:
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<ul><li>EC 4.1 includes lyases that cleave carbon–carbon bonds, such as <a href="/facts/Decarboxylase/Vfnl4VWe">decarboxylases</a> (EC 4.1.1), <a href="/facts/Aldehyde_lyases/jBS69B6G">aldehyde lyases</a> (EC 4.1.2), oxo acid lyases (EC 4.1.3), and others (EC 4.1.99)</li>
<li>EC 4.2 includes lyases that cleave carbon–oxygen bonds, such as <a href="/facts/Dehydratase/xTTCsWP2">dehydratases</a></li>
<li>EC 4.3 includes lyases that cleave carbon–nitrogen bonds</li>
<li>EC 4.4 includes lyases that cleave carbon–sulfur bonds</li>
<li>EC 4.5 includes lyases that cleave carbon–halide bonds</li>
<li>EC 4.6 includes lyases that cleave phosphorus–oxygen bonds, such as <a href="/facts/Adenylyl_cyclase/WnCSuV96">adenylyl cyclase</a> and <a href="/facts/Guanylyl_cyclase/E1l8oCYj">guanylyl cyclase</a></li>
<li>EC 4.99 includes other lyases, such as <a href="/facts/Ferrochelatase/zg7rV0CK">ferrochelatase</a></li></ul>
<h2 id="membrane-associated-lyases">Membrane-associated lyases</h2>
<p>Some lyases associate with <a href="/facts/Biological_membranes/ljBsfK4r">biological membranes</a> as <a href="/facts/Peripheral_membrane_protein/EGsWYg2e">peripheral membrane proteins</a> or anchored through a single <a href="/facts/Transmembrane_helix/D1j0PwSR">transmembrane helix</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a>
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<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/List_of_EC_numbers_(EC_4)/aAlmYQDY">List of EC numbers of enzymes belonging to category EC 4</a></li></ul>

<ul><li><a href="https://web.archive.org/web/20120716211104/http://www.chem.qmul.ac.uk/iubmb/enzyme/EC4/intro.html">EC 4 Introduction</a> from the Department of Chemistry at <a href="/facts/Queen_Mary,_University_of_London/j7FHapKf">Queen Mary, University of London</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>"Lyase". www.uniprot.org. <a href="https://www.uniprot.org/keywords/456" target="_blank">https://www.uniprot.org/keywords/456</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Superfamilies of single-pass transmembrane lyases in Membranome database <a href="http://membranome.org/protein_classes/12" target="_blank">http://membranome.org/protein_classes/12</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
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Lyase open-in-new

Lyase