EC - Myeloperoxidase

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IntEnz Enzyme Nomenclature


Accepted name:
Other names:
Systematic name:
chloride:hydrogen-peroxide oxidoreductase (hypochlorite-forming)




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, 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.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00394
Structural data: CSA , EC2PDB


  1. Agner, K.
    Advances in Enzymology 3 : 137-148 (1943).
  2. Harrison, J. E., Schultz, J.
    Studies on the chlorinating activity of myeloperoxidase.
    J. Biol. Chem. 251 : 1371-1374 (1976). [PMID: 176150]
  3. Furtmuller, P. G., Burner, U., Obinger, C.
    Reaction of myeloperoxidase compound I with chloride, bromide, iodide, and thiocyanate.
    Biochemistry 37 : 17923-17930 (1998). [PMID: 9922160]
  4. Tuynman, A., Spelberg, J. L., Kooter, I. M., Schoemaker, H. E., Wever, R.
    Enantioselective epoxidation and carbon-carbon bond cleavage catalyzed by Coprinus cinereus peroxidase and myeloperoxidase.
    J. Biol. Chem. 275 : 3025-3030 (2000). [PMID: 10652281]
  5. Klebanoff, S. J.
    Myeloperoxidase: friend and foe.
    J. Leukoc. Biol. 77 : 598-625 (2005). [PMID: 15689384]
  6. Fiedler, T. J., Davey, C. A., Fenna, R. E.
    X-ray crystal structure and characterization of halide-binding sites of human myeloperoxidase at 1.8 Å resolution.
    J. Biol. Chem. 275 : 11964-11971 (2000). [PMID: 10766826]
  7. Gaut, J. P., Yeh, G. C., Tran, H. D., Byun, J., Henderson, J. P., Richter, G. M., Brennan, M. L., Lusis, A. J., Belaaouaj, A., Hotchkiss, R. S., Heinecke, J. W.
    Neutrophils employ the myeloperoxidase system to generate antimicrobial brominating and chlorinating oxidants during sepsis.
    Proc. Natl. Acad. Sci. USA 98 : 11961-11966 (2001). [PMID: 11593004]

[EC created 2011]