Which enzyme produces reactive oxygen species that are toxic to bacteria?

Which enzyme produces reactive oxygen species that are toxic to bacteria?

• A. Lactoperoxidase
• B. Catalase
• C. Superoxide dismutase
• D. Peroxidase

Answer: (A)

Lactoperoxidase uses hydrogen peroxide to convert thiocyanate into hypothiocyanite (OSCN−), a reactive oxygen species that can attack bacterial cells. This reaction is part of an antimicrobial system present in secretions like milk and saliva, where the produced OSCN− disrupts microbial membranes and enzymes, helping to slow or stop bacterial growth. The other enzymes listed mostly handle reactive oxygen species rather than generating bactericidal oxidants: superoxide dismutase converts harmful superoxide radicals into hydrogen peroxide and oxygen, acting as a detoxifier; catalase breaks down hydrogen peroxide, also protecting cells; peroxidases generally reduce peroxides rather than produce antimicrobial ROS in secretions. Therefore, the enzyme that directly creates toxic reactive oxygen species targeting bacteria in this context is lactoperoxidase.

Lactoperoxidase uses hydrogen peroxide to convert thiocyanate into hypothiocyanite (OSCN−), a reactive oxygen species that can attack bacterial cells. This reaction is part of an antimicrobial system present in secretions like milk and saliva, where the produced OSCN− disrupts microbial membranes and enzymes, helping to slow or stop bacterial growth. The other enzymes listed mostly handle reactive oxygen species rather than generating bactericidal oxidants: superoxide dismutase converts harmful superoxide radicals into hydrogen peroxide and oxygen, acting as a detoxifier; catalase breaks down hydrogen peroxide, also protecting cells; peroxidases generally reduce peroxides rather than produce antimicrobial ROS in secretions. Therefore, the enzyme that directly creates toxic reactive oxygen species targeting bacteria in this context is lactoperoxidase.