Involved in chlorophyll degradation. Specific for the pheophorbides of the dihydroporphyrin and tetrahydroporphyrin types. Chlorophyllide a, pheophytin a and the nonfluorescent chlorophyll catabolite (NCC) are not used as substrates. H(+) + H2O + pheophorbide a = CO2 + methanol + pyropheophorbide a Inhibited by methanol and phenylmethylsulfonicfluoride (PMSF). Optimum pH is 6.5 for the native enzyme and 7.0-7.5 for the PPD-GST recombinant enzyme. Homodimer. Up-regulated by senescence. An additional type 1 isoform with the same enzymatic activity seems to exist. Belongs to the AB hydrolase superfamily.