PPOX

Role in the organism:

The PPOX gene encodes the protoporphyrinogen oxidase enzyme, which is required for the synthesis of the hem group (a non-protein component of hemoglobin). The enzyme catalyzes the penultimate step of hem group synthesis, namely the conversion of protoporphyrinogen to protoporphyrin. The last step in the reaction, the insertion of an iron molecule into a protoporphyrin molecule, is catalyzed by a ferro chelatase enzyme encoded by the FECH gene on chromosome 18.

Role in the disorder (state):

Loss of function of the PPOX enzyme results in the accumulation of protoporphyrinogen, which is excreted in the urine, giving it a dark color. The lack of a hem group and the accumulation of its metabolic precursors results in a very rare hereditary condition known as Porphyria variegata, characterized by acute abdominal pain, vomiting and constipation, and also skin lesions due to increased photosensitivity. Photosensitivity is caused by the reaction of protoporphyrinogen with oxygen, which produces free radicals (reactive molecules that can damage DNA). Symptoms are variable, while severe forms of the disease can lead to paralysis and physiological disorders.