Which enzyme reduces hydrogen peroxide in S. mutans?

Which enzyme reduces hydrogen peroxide in S. mutans?

• A. Peroxidase
• B. SOD
• C. Alkyl hydroperoxide reductase (ahp)
• D. Catalase

Answer: (C)

Hydrogen peroxide detox in many oral bacteria relies on a peroxide-reducing system rather than simple dismutation. Alkyl hydroperoxide reductase, part of the AhpCF system, directly reduces hydrogen peroxide to water. AhpC is the peroxidatic component that carries out the reduction, and AhpF supplies electrons from NADH to regenerate AhpC. This setup specifically handles peroxide load inside the cell, especially under oxidative stress. SOD’s job is to convert superoxide into hydrogen peroxide, which then must be dealt with by another enzyme. Catalase, by contrast, detoxifies hydrogen peroxide through dismutation—two molecules of H2O2 become water and oxygen—rather than reducing H2O2 directly. In S. mutans, the Ahp system provides the primary peroxide-reducing activity, making it the best fit for reducing hydrogen peroxide in this organism.

Hydrogen peroxide detox in many oral bacteria relies on a peroxide-reducing system rather than simple dismutation. Alkyl hydroperoxide reductase, part of the AhpCF system, directly reduces hydrogen peroxide to water. AhpC is the peroxidatic component that carries out the reduction, and AhpF supplies electrons from NADH to regenerate AhpC. This setup specifically handles peroxide load inside the cell, especially under oxidative stress.

SOD’s job is to convert superoxide into hydrogen peroxide, which then must be dealt with by another enzyme. Catalase, by contrast, detoxifies hydrogen peroxide through dismutation—two molecules of H2O2 become water and oxygen—rather than reducing H2O2 directly. In S. mutans, the Ahp system provides the primary peroxide-reducing activity, making it the best fit for reducing hydrogen peroxide in this organism.