Biotin (vitamin B7) is covalently bound to carboxylase enzymes. Biotinylation of which enzyme is essential for fatty acid synthesis?
- A Fatty acid synthase (FAS) complex
- B Acetyl-CoA carboxylase (ACC) ✓
- C Pyruvate dehydrogenase
- D HMG-CoA synthase
Correct answer: B. Acetyl-CoA carboxylase (ACC)
Explanation
Biotin is the prosthetic group of carboxylase enzymes (ACC, pyruvate carboxylase, propionyl-CoA carboxylase, 3-methylcrotonyl-CoA carboxylase); ACC catalyses the rate-limiting step of fatty acid synthesis (acetyl-CoA + CO2 + ATP → malonyl-CoA). Raw egg white ingestion causes biotin deficiency via avidin binding. Pyruvate dehydrogenase uses lipoic acid, TPP, FAD, NAD, CoA. FAS uses ACP (acyl carrier protein) with phosphopantetheine.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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