Alpha/beta hydrolase dephytylating specifically the Mg-free chlorophyll pigment (pheophytin), yielding pheophorbide. No activity on chlorophyll. Belongs to the chlorophyll catabolic enzymes (CCEs). Optimum temperature is 25-30 degrees Celsius. Interacts with HCAR, RCCR, PAO and the LHCII complex. Part of a SGR1-CCE-LHCII complex, which acts in chlorophyll breakdown. Up-regulated during senescence. Stay-green phenotype during leaf senescence. Delayed chlorophyll breakdown during developmental senescence. Belongs to the AB hydrolase superfamily.