myeloperoxidase (MPO)

Function: - part of host defense system of polymorphonuclear leukocytes - responsible for microbicidal activity against a wide range of organisms - in stimulated PMN, MPO catalyzes the production of hypohalous acids, primarily hypochlorous acid in physiologic situations, & other toxic intermediates that greatly enhance PMN microbicidal activity Donor + H₂O2 = oxidized donor + 2 H₂O Cl(-) + H₂O2 = HOCl + 2 H₂O Cofactor: - binds 1 Ca⁺² per heterodimer - binds 1 heme B (iron-protoporphyrin IX) group covalently per heterodimer Structure: - tetramer of two light chains & two heavy chains - belongs to the peroxidase family. XPO subfamily Compartment: lysosome Alternative splicing: named isoforms=3 Pathology: - defects in MPO are the cause of myeloperoxidase deficiency - blood levels of myeloperoxidase predictive of adverse coronary outcomes* in patients with chest pain; it is a better predictor than CRP or troponin-T; MPO accumulates in ruptured atheromatous plaques * myocardial infarction, death

Related

myeloperoxidase antibody in body fluid myeloperoxidase deficiency

General

Ca+2 binding protein glycoprotein peroxidase

Properties

SIZE: entity length = 745 aa MW = 84 kD COMPARTMENT: lysosome MOTIF: signal sequence {1-48} N-glycosylation site {N139} cysteine residue {C167} MODIFICATION: cysteine residue {C180} cysteine residue {C180} MODIFICATION: cysteine residue {C167} heme-binding site [260-260] histidine residue {H261} Ca+2-binding site SITE: 262-262 cysteine residue {C281} MODIFICATION: cysteine residue {C291} cysteine residue {C285} MODIFICATION: cysteine residue {C309} cysteine residue {C291} MODIFICATION: cysteine residue {C281} cysteine residue {C309} MODIFICATION: cysteine residue {C285} cysteine residue {C319} MODIFICATION: cysteine residue {C-INTERCHAIN} N-glycosylation site {N323} Ca+2-binding site SITE: 334-334 Ca+2-binding site SITE: 336-336 Ca+2-binding site SITE: 338-338 Ca+2-binding site SITE: 340-340 N-glycosylation site {N355} cysteine residue {C387} MODIFICATION: cysteine residue {C398} N-glycosylation site {N391} cysteine residue {C398} MODIFICATION: cysteine residue {C387} Transition state stabilizer {405-405} heme-binding site [408-408] heme-binding site [409-409] N-glycosylation site {N483} Iron [Fe]-binding site SITE: 502-502 cysteine residue {C606} MODIFICATION: cysteine residue {C663} cysteine residue {C663} MODIFICATION: cysteine residue {C606} cysteine residue {C704} MODIFICATION: cysteine residue {C730} cysteine residue {C730} MODIFICATION: cysteine residue {C704}

Database Correlations

OMIM correlations MORBIDMAP 606989 UniProt P05164 Pfam PF03098 Kegg hsa:4353 ENZYME 1.11.1.7