Which enzyme is commonly involved in degrading hydrogen peroxide in bacteria and fungi?

• A. Catalase
• B. Superoxide Dismutase
• C. Alkyl hydroperoxide reductase
• D. Peroxidase

Answer: (A)

Hydrogen peroxide is a harmful reactive oxygen species, so cells need a fast way to get rid of it. Catalase does exactly that by converting hydrogen peroxide into water and oxygen in a reaction that occurs rapidly and with high efficiency: 2 H2O2 → 2 H2O + O2. This broad, robust detox mechanism is common in both bacteria and fungi, providing essential protection against oxidative stress.

Superoxide dismutase, on the other hand, transforms superoxide radicals into hydrogen peroxide and oxygen, so it doesn’t remove hydrogen peroxide itself. Alkyl hydroperoxide reductase can reduce hydroperoxides, including some forms of hydrogen peroxide, but it isn’t the universal, primary enzyme for degrading H2O2 across bacteria and fungi. Peroxidases do reduce peroxides using electron donors, but they’re not the classic, principal means of eliminating hydrogen peroxide like catalase is.