Mycophenolate mofetil, widely used to prevent renal transplant rejection, exerts its antiproliferative effect by inhibiting which enzyme of purine metabolism?

• A Ribonucleotide reductase
• B Hypoxanthine-guanine phosphoribosyltransferase
• C Adenylosuccinate lyase
• D IMP dehydrogenase ✓

Explanation

Mycophenolic acid uncompetitively inhibits IMP dehydrogenase, blocking oxidation of IMP to xanthylate and thereby preventing GMP synthesis. Lymphocytes depend almost entirely on de novo purine synthesis rather than salvage pathways, so the drug selectively suppresses T- and D-cell proliferation while sparing most other tissues.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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