Myeloperoxidase (MPO) Protease

Myeloperoxidase (MPO) is a heme protein synthesized during myeloid differentiation that constitutes the major component of neutrophil azurophilic granules. Produced as a single chain precursor, myeloperoxidase is subsequently cleaved into a light and heavy chain. The mature myeloperoxidase is a tetramer composed of 2 light chains and 2 heavy chains. This enzyme produces hypohalous acids central to the microbicidal activity of netrophils. [provided by RefSeq, Jul 2008]

MPO: Part of the host defense system of polymorphonuclear leukocytes. It is responsible for microbicidal activity against a wide range of organisms. In the stimulated PMN, MPO catalyzes the production of hypohalous acids, primarily hypochlorous acid in physiologic situations, and other toxic intermediates that greatly enhance PMN microbicidal activity. Homodimer; disulfide-linked. Each monomer consists of a light and a heavy chain. Belongs to the peroxidase family. XPO subfamily. 3 isoforms of the human protein are produced by alternative splicing.

Protein type: Oxidoreductase; EC 1.11.2.2

Chromosomal Location of Human Ortholog: 17q23.1

Cellular Component: extracellular space; azurophil granule; mitochondrion; lysosome; nucleus; secretory granule

Molecular Function: heparin binding; peroxidase activity; metal ion binding; heme binding; chromatin binding

Biological Process: respiratory burst during defense response; response to food; removal of superoxide radicals; response to mechanical stimulus; hydrogen peroxide catabolic process; defense response; response to yeast; response to lipopolysaccharide; response to oxidative stress; defense response to fungus; negative regulation of apoptosis; aging

Disease: Myeloperoxidase Deficiency; Alzheimer Disease