Question

can excess acetyl-CoA be used in synthesis of glucose? why or why not?

Answer 1

Hi,

Yes, excess acetyl-CoA is requred to allosterically modulate ( rather cativate pathway) the  pyruvate carboxylase enzyme which is part of glucose synthesis pathway.

glucose biosynthesis from pyruvate will be promoted only when excess mitochondrial acetyl-CoA builds up beyond the immediate needs of the cell for the citric acid cycle. Once, the cell's energetic needs are being met, oxidative phosphorylation slows and consequent NADH accumulation inhibits the citric acid cycle, that results in acetyl-CoA accumulation. The excess of acetyl-CoA inhibits the pyruvate dehydrogenase complex, slowing the formation of acetyl-CoA from pyruvate, and stimulates glucose synthesis by activating pyruvate carboxylase which allows excess pyruvate to be converted to glucose.