Catalyzes the 6-electron oxidation of protoporphyrinogen-IX to form protoporphyrin-IX.
Expressed in heart, brain, placenta, lung, liver, skeletal muscle, kidney and pancreas.
Porphyrin metabolism; protoporphyrin-IX biosynthesis; protoporphyrin-IX from protoporphyrinogen-IX: step 1/1.
Involvement in disease
Defects in PPOX are the cause of variegate porphyria (VP) [MIM:176200]. Porphyrias are inherited defects in the biosynthesis of heme, resulting in the accumulation and increased excretion of porphyrins or porphyrin precursors. They are classified as erythropoietic or hepatic, depending on whether the enzyme deficiency occurs in red blood cells or in the liver. PV is the most common form of porphyria in South Africa. It is characterized by skin hyperpigmentation and hypertrichosis, abdominal pain, tachycardia, hypertension and neuromuscular disturbances. High fecal levels of protoporphyrin and coproporphyrin, increased urine uroporphyrins and iron overload are typical markers of the disease.