| 19236960 |
Kaushik VK, Kavana M, Volz JM, Weldon SC, Hanrahan S, Xu J, Caplan SL, Hubbard BK: Characterization of recombinant human acetyl-CoA carboxylase-2 steady-state kinetics. Biochim Biophys Acta. 2009 Jun;1794(6):961-7. Epub 2009 Feb 21.
Acetyl-CoA carboxylase (ACC) catalyzes the carboxylation of acetyl-CoA to form malonyl-CoA, a key metabolite in the fatty acid synthetic and oxidation pathways. The present study describes the steady-state kinetic analysis of a purified recombinant human form of the enzyme, namely ACC2, using a novel LC/MS/MS assay to directly measure malonyl-CoA formation. Four dimensional matrices, in which bicarbonate (HCO (3)(-)), ATP, acetyl-CoA, and citrate were varied, and global data fitting to appropriate steady-state equations were used to generate kinetic constants. Product inhibition studies support the notion that the enzyme proceeds through a hybrid (two-site) random Ter Ter mechanism, one that likely involves a two-step reaction at the biotin carboxylase domain. Citrate, a known activator of animal forms of ACC, activates both by increasing k (cat) and k (cat)/K (M) for ATP and acetyl-CoA. |
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