The Enzyme Database

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EC 3.1.1.82     
Accepted name: pheophorbidase
Reaction: pheophorbide a + H2O = pyropheophorbide a + methanol + CO2 (overall reaction)
(1a) pheophorbide a + H2O = C-132-carboxypyropheophorbide a + methanol
(1b) C-132-carboxypyropheophorbide a = pyropheophorbide a + CO2 (spontaneous)
For diagram of chlorophyll catabolism, click here
Other name(s): phedase; PPD
Systematic name: pheophorbide-a hydrolase
Comments: This enzyme 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. The enzyme exists in two forms: type 1 is induced by senescence whereas type 2 is constitutively expressed [1,2]. The enzyme is 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 [2]. Another enzyme, called pheophorbide demethoxycarbonylase (PDC), produces pyropheophorbide a from pheophorbide a without forming an intermediate although the precise reaction is not yet known [1].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Suzuki, Y., Doi, M. and Shioi, Y. Two enzymatic reaction pathways in the formation of pyropheophorbide a. Photosynth. Res. 74 (2002) 225–233. [PMID: 16228561]
2.  Suzuki, Y., Amano, T. and Shioi, Y. Characterization and cloning of the chlorophyll-degrading enzyme pheophorbidase from cotyledons of radish. Plant Physiol. 140 (2006) 716–725. [PMID: 16384908]
3.  Hörtensteiner, S. Chlorophyll degradation during senescence. Annu. Rev. Plant Biol. 57 (2006) 55–77. [PMID: 16669755]
[EC 3.1.1.82 created 2007]
 
 


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