Catalyzes the oxidation of protoporphyrinogen IX to protoporphyrin IX. Is involved in the biosynthesis of tetrapyrrole molecules like heme and chlorophyll. Does not use oxygen or artificial electron acceptors such as menadione or benzoquinone. 3 A + protoporphyrinogen IX = 3 AH2 + protoporphyrin IX Binds 1 heme b (iron(II)-protoporphyrin IX) group per subunit. Porphyrin-containing compound metabolism; protoporphyrin-IX biosynthesis; protoporphyrin-IX from protoporphyrinogen-IX: step 1/1. Homodimer. Belongs to the HemJ family. It is uncertain whether Met-1, Met-3 or Met-12 is the initiator.