Eosinophil peroxidase

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Eosinophil peroxidase
External IDs OMIM131399 MGI107569 HomoloGene20144 ChEMBL: 2438 GeneCards: EPX Gene
EC number
Species Human Mouse
Entrez 8288 13861
Ensembl ENSG00000121053 ENSMUSG00000052234
UniProt P11678 P49290
RefSeq (mRNA) NM_000502 NM_007946
RefSeq (protein) NP_000493 NP_031972
Location (UCSC) Chr 17:
56.27 – 56.28 Mb
Chr 11:
87.86 – 87.88 Mb
PubMed search [1] [2]

Eosinophil peroxidase is a haloperoxidase enzyme that in humans is encoded by the EPX gene.[1][2] The enzyme is a heterodimeric 71-77 kD peroxidase consisting of a heavier glycosylated chain and a lighter nonglycosylated chain. This enzyme prefers bromide over chloride as a substrate, converting it to cytotoxic hypobromite.


In the presence of H2O2 formed by the eosinophil, and either chloride or bromide ions, eosinophil peroxidase provides a potent mechanism by which eosinophils kill multicellular parasites (such as, for example, the nematode worms involved in filariasis); and also certain bacteria (such as tuberculosis bacteria). Eosinophil peroxidase is a haloperoxidase that preferentially uses bromide over chloride for this purpose, generating hypobromite (hypobromous acid).[3] The enzyme is also capable of oxidizing thiocyanate (SCN) and uses it as a co-substrate, with optimal concentrations occurring at about normal plasma levels.[4]

Eosinophil peroxidase is also partly responsible for tissue remodeling.

Role in pathology[edit]

The oxidizing compounds produced by eosinophil peroxidase have been implicated in the inflammatory pathology of several disease states, including asthma.[5]

See also[edit]


  1. ^ Sakamaki K, Tomonaga M, Tsukui K, Nagata S (October 1989). "Molecular cloning and characterization of a chromosomal gene for human eosinophil peroxidase". J. Biol. Chem. 264 (28): 16828–36. PMID 2550461. 
  2. ^ Ten RM, Pease LR, McKean DJ, Bell MP, Gleich GJ (May 1989). "Molecular cloning of the human eosinophil peroxidase. Evidence for the existence of a peroxidase multigene family". J. Exp. Med. 169 (5): 1757–69. doi:10.1084/jem.169.5.1757. PMC 2189302. PMID 2541222. 
  3. ^ Mayeno AN, Curran AJ, Roberts RL, Foote CS (April 1989). "Eosinophils preferentially use bromide to generate halogenating agents". J. Biol. Chem. 264 (10): 5660–8. PMID 2538427. 
  4. ^ Tahboub YR, Galijasevic S, Diamond MP, Abu-Soud HM (2005). "Thiocyanate modulates the catalytic activity of mammalian peroxidases". J. Biol. Chem. 280 (28): 26129–36. doi:10.1074/jbc.M503027200. PMID 15894800. 
  5. ^ van Dalen CJ, Kettle AJ (August 2001). "Substrates and products of eosinophil peroxidase". Biochem. J. 358 (Pt 1): 233–9. doi:10.1042/0264-6021:3580233. PMC 1222052. PMID 11485572. 

Further reading[edit]

External links[edit]

From JC Segen Dictionary of Modern Medicine database