Catalyzes the key reaction of chlorophyll catabolism, porphyrin macrocycle cleavage of pheophorbide a (pheide a) to a primary fluorescent catabolite (pFCC). Works in a two-step reaction with pheophorbide a oxygenase (PaO) by reducing the C20/C1 double bond of the intermediate, RCC. 2 oxidized [2Fe-2S]-[ferredoxin] + primary fluorescent chlorophyll catabolite = 3 H(+) + red chlorophyll catabolite + 2 reduced [2Fe-2S]-[ferredoxin] Porphyrin-containing compound metabolism; chlorophyll degradation. Homodimer. In etiolated and green primary leaves. Low amount in roots. Decreases during leaf senescence, but still present after 8 days of dark-induced senescence. The N-terminus is blocked.