Sandbox Reserved 774: Difference between revisions
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The binding of substrates and release of products can be random, fully ordered, or a combination of both. It operates on a Bi-Bi mechanism. A study that employed product inhibitors CoA and acetylated (Lys14Ac) H3 peptide and dead-end inhibitor desulfo-CoA in order to determine the order of substrate binding has yielded results consistent with a fully ordered Bi-Bi kinetic mechanism where AcCoA is the first substrate to bind, and CoA is the last product that is released. It is also important to note that the transcriptional co-activator GCN5 from yeast (yGCN5) is a histone acetyltransferase that is essential for the activation of target genes. Bi-substrate kinetic analysis using acetyl-coenzyme A and an H3 histone synthetic peptide indicated that both substrates must bind to form a ternary complex before catalysis. Product inhibition studies revealed that the product CoA was a competitive inhibitor as opposed to AcCoA. Desulfo-CoA, a dead end inhibitor, also demonstrated simple competitive inhibition versus AcCoA. Acetylated (Lys14Ac) H3 peptide displayed noncompetitive inhibition against both H3 peptide and AcCoA.<ref>Tanner, et al. "Kinetic Mechanism of the Histone Acetyltransferase GCN5 from Yeast." J. Biol. Chem. 275.29 (2000): 2-9. Web. 26 Nov. 2013.</ref> | The binding of substrates and release of products can be random, fully ordered, or a combination of both. It operates on a Bi-Bi mechanism. A study that employed product inhibitors CoA and acetylated (Lys14Ac) H3 peptide and dead-end inhibitor desulfo-CoA in order to determine the order of substrate binding has yielded results consistent with a fully ordered Bi-Bi kinetic mechanism where AcCoA is the first substrate to bind, and CoA is the last product that is released. It is also important to note that the transcriptional co-activator GCN5 from yeast (yGCN5) is a histone acetyltransferase that is essential for the activation of target genes. Bi-substrate kinetic analysis using acetyl-coenzyme A and an H3 histone synthetic peptide indicated that both substrates must bind to form a ternary complex before catalysis. Product inhibition studies revealed that the product CoA was a competitive inhibitor as opposed to AcCoA. Desulfo-CoA, a dead end inhibitor, also demonstrated simple competitive inhibition versus AcCoA. Acetylated (Lys14Ac) H3 peptide displayed noncompetitive inhibition against both H3 peptide and AcCoA.<ref>Tanner, et al. "Kinetic Mechanism of the Histone Acetyltransferase GCN5 from Yeast." J. Biol. Chem. 275.29 (2000): 2-9. Web. 26 Nov. 2013.</ref> | ||
[[Image:Hpa2_Kinetic_Mechanism.jpg]] | [[Image:Hpa2_Kinetic_Mechanism.jpg]][[Image:Kinetic_Mechanism.jpg]] | ||
==Chemical Mechanism== | ==Chemical Mechanism== | ||