Question

List two toxic oxygen species (both name and chemical formula) and enzymes that detoxify them.

Answer 1

The two toxic oxygen species are hydrogen peroxide (H₂O₂) and superoxide anion (^.O₂^-).

These toxic species can have drastic effects on a cell which include lipid peroxidation, DNA or RNA damage, oxidation of enzyme cofactors leading to enzyme deactivation and oxidation of amino acids in proteins. Owing to this damage, these toxic species need to be eliminated.

Hydrogen peroxide is eliminated by the action of the enzyme catalase which converts it into water and oxygen. The reaction can be represented as

2H₂O₂ 2H₂O + O₂

Superoxide anion is eliminated by the action of enzyme superoxide dismutase (SOD) which converts it into hyrogen peroxide and oxygen. The reaction can be represented as

^.O₂^- + ^.O₂^- + 2H⁺ H₂O₂ + O₂