Selenium is an essential trace element incorporated into selenoproteins. The MOST important selenoprotein protecting cells from oxidative damage is:

• A Thioredoxin reductase (TrxR) only
• B Iodothyronine deiodinase only
• C Glutathione peroxidase (GPx) ✓
• D Selenoprotein P as primary antioxidant

Explanation

Glutathione peroxidase (GPx) family enzymes contain selenocysteine at their active site, which is essential for catalytic activity. GPx reduces hydrogen peroxide and lipid hydroperoxides to water or alcohols using reduced glutathione as electron donor, preventing oxidative damage to membranes and DNA. Selenium deficiency reduces GPx activity, contributing to Keshan disease (dilated cardiomyopathy) and Kashin-Beck disease. Thioredoxin reductase and iodothyronine deiodinases also require selenium but GPx is the primary antioxidant selenoprotein.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.