Table 3.

Examples of substrates oxidized through the halogenation and peroxidase pathways of MPO.

MPO Activity or cycle	Reactants	Products
Halogenation	Halides and pseudohalides	Two-electron oxidized products.
Examples	Cl−, Br−, I−, SCN−	HOCl, HOBr, HOI, HOSCN
Peroxidase	Aromatic compounds (both endogenous and exogenous); nitric oxide derivatives; small inorganic compounds	One electron oxidation products, most of which are subsequently oxidized.
Examples	Ascorbic acid, tyrosine, arylamine drugs, hydrogen sulphide	Dehydroascorbyl radical (a stable radical), Tyrosine phenoxyl radical leading to dityrosine, arylamine radicals leading to multiple products, including oxidizing species that can damage proteins and DNA, hydrogen sulphide radicals