-!- Is present in phagosomes of neutrophils and monocytes, where the hypochlorite produced is strongly bactericidal. -!- It differs from EC 1.11.1.10 in its preference for formation of hypochlorite over the chlorination of organic substrates under physiological conditions (pH 5-8). -!- Hypochlorite in turn forms a number of antimicrobial products (Cl(2), chloramines, hydroxyl radical, singlet oxygen). -!- MPO also oxidizes bromide, iodide and thiocyanate. -!- In the absence of halides, it oxidizes phenols and has a moderate peroxygenase activity toward styrene.