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 . Another enzyme, called pheophorbide demethoxycarbonylase (PDC), produces pyropheophorbide a from pheophorbide a without forming an intermediate although the precise reaction is not yet known .
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SYSTEMATIC NAME
IUBMB Comments
pheophorbide-a hydrolase
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].
the enzyme catalyzes the conversion of pheophorbide a to a precursor of pyropheophorbide a (C-132-carboxyl-pyropheophorbide a). The precursor is then decarboxylated non-enzymatically to yield pyropheophorbide
the enzyme catalyzes the conversion of pheophorbide a to a precursor of pyropheophorbide a, C-132-carboxylpyropheophorbide a, by demethylation, and then the precursor is decarboxylated non-enzymatically to yield pyropheophorbide a, Phedase type 1
the enzyme catalyzes the conversion of pheophorbide a to a precursor of pyropheophorbide a, C-132-carboxylpyropheophorbide a, by demethylation, and then the precursor is decarboxylated non-enzymatically to yield pyropheophorbide a, Phedase type 2
recombinant MES16 protein is able to demethylate both pheophorbide a and primary fluorescent chlorophyll catabolites (pFCC), but in vivo, MES16 specifically acts on FCCs
in slow drying the phedase shows an increase of 0.94fold of its initial activity in fresh before 24 h but decreases sharply as time goes on with 25% activity remaining ultimately. Phedase of the 50°C samples in fast drying show a constant decrease
MES16-deficient mutants (mes16) are still able to degrade chlorophyll, but they accumulate FCCs (fluorescent chlorophyll) and NCCs (nonfluorescent chlorophyll) catabolites with an intact C132-carboxymethyl group. As a consequence, FCC-to-NCC isomerization is compromised and the mutants accumulate large quantities of FCCs, which causes senescent leaves to fluoresce under UV light
recombinant PPD is produced using a glutathione S-transferase (GST) fusion system. The PPD and GST genes are fused to a pGEX-2T vector and expressed in Escherichia coli BL21(DE3)pLysS strain under the control of a T7 promoter as a fusion protein
Two enzymatic reaction pathways in the formation of pyropheophorbide a
Photosynth. Res.
74
225-233
2002
Arabidopsis thaliana, Brassica rapa subsp. oleifera, Brassica rapa subsp. pekinensis, Brassica rapa subsp. chinensis, Brassica napus, Brassica oleracea, Chenopodium album, Nasturtium officinale, no activity in Chlamydomonas reinhardtii, no activity in Equisetum arvense, no activity in Ginkgo biloba, no activity in Hordeum vulgare, no activity in Pisum sativum, no activity in Spinacia oleracea, Raphanus sativus, no activity in Rumex acetosa, no activity in Camellia sinensis, no activity in Corchorus olitorius, no activity in Perilla frutescens, no activity in Chrysanthemum coronarium, no activity in Petroselinum sativum, Hypolepis punctata, no activity in Lepisorus thunbergianus
Expression and purification of pheophorbidase, an enzyme catalyzing the formation of pyropheophorbide during chlorophyll degradation: comparison with the native enzyme
MES16, a member of the methylesterase protein family, specifically demethylates fluorescent chlorophyll catabolites during chlorophyll breakdown in Arabidopsis