Which condition would increase pyruvate dehydrogenase (PDH) activity?

Which condition would increase pyruvate dehydrogenase (PDH) activity?

• A. High pyruvate, NAD+, and CoA
• B. High acetyl-CoA and NADH
• C. High ATP
• D. High pyruvate, NAD+, and CoA

Answer: (A)

PDH activity rises when the cell needs to funnel pyruvate into the mitochondrial energy pathway. When pyruvate is abundant and the key cofactors NAD+ and CoA are available, the PDH complex has the substrates it requires to efficiently convert pyruvate into acetyl-CoA, generating NADH in the process. This situation favors an active, dephosphorylated PDH and forward flux into the TCA cycle. In contrast, signs of energy abundance—high ATP, high NADH, or high acetyl-CoA—activate PDH kinase, which phosphorylates and inhibits PDH, reducing its activity. Therefore, the condition with high pyruvate, NAD+, and CoA best increases PDH activity, while high acetyl-CoA/NADH or high ATP would diminish it. The duplicate option with the same substrate set simply reiterates the same activating condition.

PDH activity rises when the cell needs to funnel pyruvate into the mitochondrial energy pathway. When pyruvate is abundant and the key cofactors NAD+ and CoA are available, the PDH complex has the substrates it requires to efficiently convert pyruvate into acetyl-CoA, generating NADH in the process. This situation favors an active, dephosphorylated PDH and forward flux into the TCA cycle. In contrast, signs of energy abundance—high ATP, high NADH, or high acetyl-CoA—activate PDH kinase, which phosphorylates and inhibits PDH, reducing its activity. Therefore, the condition with high pyruvate, NAD+, and CoA best increases PDH activity, while high acetyl-CoA/NADH or high ATP would diminish it. The duplicate option with the same substrate set simply reiterates the same activating condition.