Glutathione peroxidase is a selenoenzyme that reduces hydrogen peroxide and lipid hydroperoxides using reduced glutathione as the electron donor. The selenium at its active site is incorporated as which modified amino acid, and what is the cardiac manifestation of severe dietary selenium deficiency?

• A Cysteic acid; beriberi
• B Selenomethionine; hemochromatosis
• C Selenocysteine; Keshan disease (endemic cardiomyopathy) ✓
• D Homocysteine; Wernicke encephalopathy

Explanation

Glutathione peroxidase contains selenocysteine at its active site, encoded by the UGA codon. Severe selenium deficiency causes Keshan disease, a congestive cardiomyopathy endemic to selenium-deficient regions of China. Selenomethionine is a storage form, not the catalytic residue. The other options pair unrelated amino acids with unrelated deficiency diseases.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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