Coproporphyrinogen III oxidase (CPX) is an enzyme involved in the biosynthesis
of tetrapyrroles, catalyzing the oxidative decarboxylation of coproporphyrinogen III to
protoporphyrinogen IX. In bacteria and yeast this enzyme is cytosolic, in animals it is
mitochondrial, and in each it functions to produce heme. However, in all plants
investigated, the...