Biotin deficiency causes alopecia, dermatitis, and neurological symptoms. Biotin serves as a prosthetic group for carboxylases. Which enzyme is NOT biotin-dependent?

• A Pyruvate carboxylase — IS biotin-dependent
• B Acetyl-CoA carboxylase — IS biotin-dependent
• C Transcarboxylase — IS biotin-dependent; the enzyme NOT biotin-dependent among the choices is pyruvate decarboxylase (part of PDH), which uses TPP not biotin ✓
• D Propionyl-CoA carboxylase — IS biotin-dependent

Explanation

Pyruvate decarboxylase (E1 component of pyruvate dehydrogenase complex) uses thiamine pyrophosphate (TPP), not biotin. Biotin-dependent carboxylases in humans include: pyruvate carboxylase (pyruvate → OAA), acetyl-CoA carboxylase (acetyl-CoA → malonyl-CoA), propionyl-CoA carboxylase (propionyl-CoA → methylmalonyl-CoA), and 3-methylcrotonyl-CoA carboxylase (leucine catabolism). Holocarboxylase synthetase attaches biotin to all four enzymes; its deficiency mimics biotin deficiency.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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