After a high-protein meal, increased acetyl-CoA allosterically activates pyruvate carboxylase. The physiologic purpose of this activation is:

• A To commit pyruvate toward gluconeogenesis exclusively
• B To replenish oxaloacetate consumed by accelerated citrate synthase activity ✓
• C To divert acetyl-CoA into ketogenesis
• D To inhibit the pyruvate dehydrogenase complex irreversibly

Explanation

Oxaloacetate is catalytic and is drained when acetyl-CoA flux through citrate synthase rises. Pyruvate carboxylase is the principal anaplerotic enzyme of the TCA cycle, converting pyruvate to oxaloacetate using biotin and ATP, and acetyl-CoA is its obligatory allosteric activator. While the same product can feed gluconeogenesis, the immediate biochemical rationale tested here is anaplerotic replacement of oxaloacetate.

Reference: Lippincott's Illustrated Reviews: Biochemistry, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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