Regulation
The activity of the enzyme is controlled in several ways. The essential lysine residue in the active site plays an important role in regulation of activity. The lysine molecule can be deacetylated by another class of enzyme called sirtuins, to be more specific, Sirt3. This action increases activity of this enzyme. The exact location of the lysine residue varies between species, occurring at Lys-642 in humans, but is always present in the active site of the enzyme. Since there is an essential allosteric change that occurs with the binding of an AMP molecule, the presence of AMP can contribute to regulation of the enzyme. Concentration of AMP must be high enough so that it can bind in the allosteric binding site and allow the other substrates to enter the active site. Also, copper ions deactivate acetyl Co-A synthetase by occupying the proximal site of the A-cluster active site, which prevents the enzyme from accepting a methyl group to participate in the Wood-Ljungdahl Pathway. The presence of all the reactants in the proper concentration is also needed for proper functioning as in all enzymes. Acetyl—CoA synthetase is also produced when it is needed for fatty acid synthesis, but, under normal conditions, the gene is inactive and has certain transcriptional factors that activate transcription when necessary. In addition to sirtuins, protein deacetylase (AcuC) also can modify acetyl—CoA synthetase at a lysine residue. However, unlike sirtuins, AcuC does not require NAD+ as a cosubstrate.
Read more about this topic: Acetyl-Co A Synthetase
Famous quotes containing the word regulation:
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—Margarethe Cammermeyer (b. 1942)
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—David Hume (1711–1776)