Membrane-bound myeloperoxidase (MPO) produces hypochlorous acid (HOCl)

Stable Identifier
Reaction [transition]
Homo sapiens
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Granule-derived cationic MPO protein can attach to negatively charged proteins and membrane epitopes of ingested bacteria (Selvaraj RJ et al. 1978; Miyasaki KT et al. 1987). This could be a way of directing HOCl for effective killing (Klebanoff SJ et al. 1999).

MPO is a heme enzyme that uses hydrogen peroxide to oxidize chloride to hypochlorous acid. MPO reacts with hydrogen peroxide, which is produced by stimulated neutrophils, to form the redox intermediate compound I (Winterbourn CC et al 2006; Davies MJ 2011; Pattison DI et al. 2012). Compound I is strongly oxidizing and reacts with a variety of substrates such as halide and pseudo-halide ions to produce hypohalous acids (HOX where X = Cl, Br, SCN). Its main physiological substrate is assumed to be chloride, which undergoes a two-electron oxidation to form hypochlorous acid (HOCl) (Winterbourn CC et al 2006; Davies MJ 2001; Pattison DI et al. 2012).

Literature References
PubMed ID Title Journal Year
17074761 Modeling the reactions of superoxide and myeloperoxidase in the neutrophil phagosome: implications for microbial killing

Hampton, MB, Livesey, JH, Kettle, AJ, Winterbourn, CC

J. Biol. Chem. 2006
22348603 Reactions and reactivity of myeloperoxidase-derived oxidants: differential biological effects of hypochlorous and hypothiocyanous acids

Hawkins, CL, Davies, MJ, Pattison, DI

Free Radic. Res. 2012
Catalyst Activity

peroxidase activity of MPO:ferriheme:bacterial cell surface [phagocytic vesicle lumen]

Orthologous Events
Cross References
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