Involved in the heme biosynthesis. Catalyzes the aerobic oxidative decarboxylation of propionate groups of rings A and B of coproporphyrinogen-III to yield the vinyl groups in protoporphyrinogen-IX (By similarity). coproporphyrinogen III + 2 H(+) + O2 = 2 CO2 + 2 H2O + protoporphyrinogen IX Porphyrin-containing compound metabolism; protoporphyrin-IX biosynthesis; protoporphyrinogen-IX from coproporphyrinogen-III (O2 route): step 1/1. Homodimer. Expressed in erythroid cells. Expressed in liver (PubMed:8407975). Acetylation of Lys-360 is observed in liver mitochondria from fasted mice but not from fed mice. Belongs to the aerobic coproporphyrinogen-III oxidase family. Truncated N-terminus.