In exercising skeletal muscles, pyruvate oxidation in the TCA cycle is stimulated by which of the following? A) allosteric activation of isocitrate dehydrogenase by NADH B) allosteric activation of malate dehydrogenase by NAD⁺ C) increased product inhibition of citrate synthase by oxaloacetate D) phosphorylation of α-ketoglutarate dehydrogenase to an inactive form E) stimulation of pyruvate dehydrogenase activity by Ca²⁺

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Quizplus · Accepted Answer

The Answer is E
EXPLANATION: Muscle contraction results in release of stored calcium ion from sarcoplasmic reticulum. The released calcium allosterically inhibits the activity of the PDH kinases. Reduced activity of PDH kinases results in reduced phosphorylation of the PDHc thus, allowing for greater oxidation of pyruvate.

In Exercising Skeletal Muscles, Pyruvate Oxidation in the TCA Cycle