An endemic cardiomyopathy characterised by multifocal myocardial necrosis was described in regions of China with soil poor in a trace element. This element functions biochemically as:

• A A structural component of methionine synthase requiring adenosylcobalamin
• B The prosthetic group of glutathione peroxidase, protecting membranes from lipid peroxidation ✓
• C A cofactor for superoxide dismutase in the mitochondrial matrix
• D An activator of pyruvate carboxylase in gluconeogenesis

Explanation

Keshan disease, an endemic dilated cardiomyopathy seen in selenium-deficient areas of China, arises from loss of glutathione peroxidase activity, since selenium is present in the enzyme as selenocysteine at its active site. Without adequate selenium, hydrogen peroxide and lipid hydroperoxides accumulate in cardiac myocyte membranes causing necrosis. Manganese and copper-zinc superoxide dismutases are distinct metalloenzymes, biotin activates pyruvate carboxylase, and cobalamin is the cofactor of methionine synthase.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.