Which of the following is most effective for gluconeogenesis:: (A) Fructose 2,6 bisphosphate inhibits fructose 1,6 Bisphosphatase, (B) Acetyl CoA activates Pyruvate carboxylase, (C) Acetyl CoA inhibits Pyruvate carboxylase, (D) Citrate activates Acetyl CoA carboxylase
Answer is B. Acetyl CoA can never be conveed to glucose but acetyl CoA activates the first step of gluconeogenesis (pyruvate carboxylase). When OAA is used for gluconeogenesis in fasting state, then acetyl CoA is not used up in TCA. So acetyl CoA accumulates. acetyl CoA - allosteric activator of pyruvate carboxylase. This reaction is anaplerotic reaction (replenish TCA intermediate OAA). Option 4- Activation of Acetyl CoA carboxylase by Citrate leads to increased fatty acid synthesis and not gluconeogenesis. Option 1- Fructose 2,6 bisphosphate inhibits fructose 1,6 Bisphosphatase (an enzyme of gluconeogenesis) hence decrease gluconeogenesis.