coproporphyrinogen III + 2 S-adenosyl-L-methionine => protoporphyrinogen IX + 2 5'-deoxyadenosine + 2 L-methionine + 2 CO2
coproporphyrinogen iii + 2 s-adenosyl-l-methionine => protoporphyrinogen ix + 2 5'-deoxyadenosine + 2 l-methionine + 2 co2