ROOR' + electron donor (2 e-) + 2H+ → ROH + R'OH
Many of these compounds are optimally designed to process hydrogen peroxide.
The nature of the electron donor is very dependent on the specific nature of the enzyme itself. For a compound such as horseradish peroxidase, the number of organic compounds it can use as electron donors is substantial. Horseradish peroxidase has a broad and accessible active site and many compounds can reach the site of the reaction. For a compound such as cytochrome c peroxidase, the compounds that donate electrons are very specific, because there is a very closed active site.
Peroxidases are sometimes used as histological markers. Cytochrome c peroxidase is used as a soluble, easily purified model for cytochrome c oxidase.
Glutathione peroxidase is a peroxidase found in humans containing selenocysteine.
see also: peroxide, catalase, hemoprotein