A patient with hereditary hemochromatosis has iron overload. The excess free iron catalyzes the Fenton reaction. Which endogenous protein normally sequesters iron to prevent this reaction, acting as an antioxidant by depriving the Fenton reaction of its substrate?
- A Transferrin ✓
- B Ferritin
- C Haptoglobin
- D Hemopexin
Correct answer: A. Transferrin
Explanation
Transferrin binds ferric iron (Fe3+) in the blood with extremely high affinity, preventing free iron from participating in the Fenton reaction. Ferritin stores intracellular iron, but transferrin is the primary extracellular iron-sequestering antioxidant protein. Haptoglobin binds free hemoglobin, and hemopexin binds free heme.
Reference: Harper's Illustrated Biochemistry, 31st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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