protoporphyrinogen IX + 3 a quinone => protoporphyrin IX + 3 a quinol
protoporphyrinogen ix + 3 a quinone => protoporphyrin ix + 3 a quinol
protoporphyrinogen IX + 3 a quinone => protoporphyrin IX + 3 a quinol
protoporphyrinogen ix + 3 a quinone => protoporphyrin ix + 3 a quinol