Oxidoreductases;
Acting on a peroxide as acceptor;
Peroxygenases
BRITE hierarchy

chloride:hydrogen-peroxide oxidoreductase (hypochlorite-forming)

Cl- + H2O2 + H+ = HClO + H2O [RN:R09564]

R09564;
(other) R11906
Reaction

Cl- [CPD:C00698];
H2O2 [CPD:C00027];
H+ [CPD:C00080]

Contains calcium and covalently bound heme (proximal ligand histidine). It is present in phagosomes of neutrophils and monocytes, where the hypochlorite produced is strongly bactericidal. It differs from EC 1.11.1.10 chloride peroxidase 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 (Cl2, 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.

EC 1.11.2.2 created 2011

1

Agner, K.

Myeloperoxidase.

Adv Enzymol 3:137-148 (1943)

2  [PMID:176150]

Harrison JE, Schultz J

Studies on the chlorinating activity of myeloperoxidase.

J Biol Chem 251:1371-4 (1976)

3  [PMID:9922160]

Furtmuller PG, Burner U, Obinger C

Reaction of myeloperoxidase compound I with chloride, bromide, iodide, and thiocyanate.

Biochemistry 37:17923-30 (1998)
DOI:10.1021/bi9818772

4  [PMID:10652281]

Tuynman A, Spelberg JL, Kooter IM, Schoemaker HE, Wever R

Enantioselective epoxidation and carbon-carbon bond cleavage catalyzed by Coprinus cinereus peroxidase and myeloperoxidase.

J Biol Chem 275:3025-30 (2000)
DOI:10.1074/jbc.275.5.3025

5  [PMID:15689384]

Klebanoff SJ

Myeloperoxidase: friend and foe.

J Leukoc Biol 77:598-625 (2005)
DOI:10.1189/jlb.1204697

6  [PMID:10766826]

Fiedler TJ, Davey CA, Fenna RE

X-ray crystal structure and characterization of halide-binding sites of human myeloperoxidase at 1.8 A resolution.

J Biol Chem 275:11964-71 (2000)
DOI:10.1074/jbc.275.16.11964

[hsa:4353]

7  [PMID:11593004]

Gaut JP, Yeh GC, Tran HD, Byun J, Henderson JP, Richter GM, Brennan ML, Lusis AJ, Belaaouaj A, Hotchkiss RS, Heinecke JW

Neutrophils employ the myeloperoxidase system to generate antimicrobial brominating and chlorinating oxidants during sepsis.

Proc Natl Acad Sci U S A 98:11961-6 (2001)
DOI:10.1073/pnas.211190298