Eosinophil peroxidase (EPO)

Eosinophil peroxidase is a highly cationic, α-helical heme enzyme composed of a heavy and light chain, derived by proteolytic processing from a single precursor protein. It catalyzes the formation of reactive hypohalous acids (especially from bromide and iodide) using hydrogen peroxide as an oxidant, which helps kill invading microbes and can contribute to tissue damage in inflammatory diseases. The enzyme is highly expressed in eosinophils—specialized immune cells involved in allergic responses, parasite defense, and certain pathological inflammatory syndromes. Its biochemical properties and structural features closely resemble those of myeloperoxidase but differ enough to support specific functional roles. Eosinophil peroxidase’s activity in redirecting eosinophils' toxic output extracellularly is crucial for antimicrobial defense but also a driver of tissue remodeling and damage seen in asthma and other eosinophil-mediated disorders.

Other names

Eosinophil peroxidaseEPXEPOEPPEosinophil peroxidase preproprotein

Inhibition of oxidative activity (reducing reactive oxygen species and tissue damage in inflammatory disease contexts). Suppression of halide oxidation, potentially regulating downstream inflammatory or thrombotic signaling.