Catalase is a major enzymatic defence against hydrogen peroxide. Where is this enzyme predominantly located, and which prosthetic group does it use?

• A Mitochondrial matrix, copper
• B Cytosol, selenium
• C Peroxisomes, heme iron ✓
• D Endoplasmic reticulum, flavin adenine dinucleotide

Explanation

Catalase is concentrated in peroxisomes, where it degrades the hydrogen peroxide generated by peroxisomal oxidases such as D-amino acid oxidase and fatty acyl-CoA oxidase. It is a tetrameric enzyme containing four heme groups that allow both catalatic breakdown of H2O2 to water and oxygen and peroxidatic activity. Selenium is the cofactor of glutathione peroxidases, not catalase, which is the key distractor distinction.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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