-!- Forms part of the chlorophyll degradation pathway, and is found in higher plants and in algae. -!- In higher plants it participates in de-greening processes such as fruit ripening, leaf senescence, and flowering. -!- Exists in two forms: type 1 is induced by senescence whereas type 2 is constitutively expressed. -!- Highly specific for pheophorbide as substrate (with a preference for pheophorbide a over pheophorbide b) as other chlorophyll derivatives such as protochlorophyllide a, pheophytin a and c, chlorophyll a and b, and chlorophyllide a cannot act as substrates. -!- Another enzyme, called pheophorbide demethoxycarbonylase (PDC), produces pyropheophorbide a from pheophorbide a without forming an intermediate although the precise reaction is not yet known.