Coproporphyrinogen-III oxidase, mitochondrial (CPOX)

Coproporphyrinogen-III oxidase (CPOX) is a mitochondrial enzyme that catalyzes the sixth step in heme biosynthesis: the oxidative decarboxylation of coproporphyrinogen III to protoporphyrinogen IX[1][2]. The enzyme is encoded by the CPOX gene and primarily expressed in the liver, bone marrow, and blood, where heme production is critical[1][2]. Deficiency of CPOX activity due to genetic mutations results in hereditary coproporphyria, an acute hepatic porphyria characterized by episodes of abdominal pain, neuropsychiatric symptoms, and/or photosensitivity[3]. CPOX is a homodimeric protein localized to the mitochondrial intermembrane space and is unique among oxidases in performing its reactions in a metal- and cofactor-independent manner[3]. Its function is essential for the biosynthesis of hemoproteins including hemoglobin, myoglobin, and cytochromes[1][2].

Other names

Coproporphyrinogen oxidaseCPOCPXCOXHCPCoprogen oxidaseCoproporphyrinogenaseHARPO

Enzyme replacement or substrate reduction (not direct but disease management: heme arginate provides heme to downregulate endogenous biosynthesis and alleviate symptoms in porphyria attacks)[3]