Myeloperoxidase
Myeloperoxidase (MPO) is an enzyme most abundantly present in neutrophil granulocytes. It is a lysosomal protein stored in azurophilic granules of the neutrophil. MPO has a heme pigment which causes its green color in secretions rich in neutrophils, such as pus and some forms of mucus. It uses hydrogen peroxidase to convert chloride to hypochlorous acid. The produced hypochlorous acid reacts with and destroys bacteria. In many inflammatory pathologies, such as cystic fibrosis and rheumatoid arthritis, neutrophils are also causing tissue damage. It is also produced when arteries are inflamed and have rupture-prone fatty deposits. An inflammation in the arteries can lead to a blood clot and eventually to a heart attack or stroke.
Swiss-Prot Accession Number: P05164
