In the HMP shunt (pentose phosphate pathway), Glucose-6-phosphate dehydrogenase (G6PD) is the rate-limiting enzyme. Its product NADPH is MOST critical in erythrocytes for which specific reaction?

• A Reduction of NAD+ to NADH for ATP production
• B Reduction of glutathione disulfide (GSSG) to reduced glutathione (GSH) ✓
• C Conversion of ribose-5-phosphate to ATP
• D Synthesis of heme from succinyl-CoA

Explanation

In RBCs, NADPH produced by G6PD is obligatorily required to regenerate reduced glutathione (GSH) via glutathione reductase. GSH neutralises reactive oxygen species and maintains hemoglobin in the functional ferrous (Fe2+) state. G6PD deficiency depletes GSH, leaving RBCs vulnerable to oxidant-induced hemolysis. RBCs do not regenerate NAD+ via NADPH; that role is served by the Embden-Meyerhof pathway.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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