Ketone bodies are synthesised in the liver during fasting, yet the liver itself derives almost no energy from them. The reason is that hepatocytes lack which enzyme?

• A HMG-CoA lyase
• B Succinyl-CoA:3-ketoacid CoA transferase (thiophorase) ✓
• C Beta-hydroxybutyrate dehydrogenase
• D Acetoacetyl-CoA thiolase

Explanation

Extrahepatic tissues activate acetoacetate to acetoacetyl-CoA using thiophorase (SCOT), which transfers CoA from succinyl-CoA. Hepatocytes lack this enzyme, so they produce ketones but cannot consume them, sparing hepatic glucose for obligate users. All three distractors are present in liver: HMG-CoA lyase cleaves HMG-CoA to acetoacetate, and the dehydrogenase and thiolase participate in synthesis.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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