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EC 1.14.15.17 Details
show Brenda entryEC number
1.14.15.17
Accepted name
pheophorbide a oxygenase
Reaction
pheophorbide a + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = red chlorophyll catabolite + 2 oxidized ferredoxin [iron-sulfur] cluster (overall reaction);;(1a) pheophorbide a + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = epoxypheophorbide a + 2 oxidized ferredoxin [iron-sulfur] cluster + H2O;;(1b) epoxypheophorbide a + H2O = red chlorophyll catabolite (spontaneous)
Other name(s)
pheide a monooxygenase,
pheide a oxygenase,
PaO,
PAO
Systematic name
pheophorbide-a,ferredoxin:oxygen oxidoreductase (biladiene-forming)
Comment
This enzyme catalyses a key reaction in chlorophyll degradation, which occurs during leaf senescence and fruit ripening in higher plants. The enzyme from Arabidopsis contains a Rieske-type iron-sulfur cluster [2] and requires reduced ferredoxin, which is generated either by NADPH through the pentose-phosphate pathway or by the action of photosystem I [4]. While still attached to this enzyme, the product is rapidly converted into primary fluorescent chlorophyll catabolite by the action of EC 1.3.7.12, red chlorophyll catabolite reductase [2,6]. Pheophorbide b acts as an inhibitor. In 18O2 labelling experiments, only the aldehyde oxygen is labelled, suggesting that the other oxygen atom may originate from H2O [1].
History
created 2007 as EC 1.14.12.20, transferred 2016 to EC 1.14.15.17
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1 Oxidoreductases
1.1 Acting on the CH-OH group of donors
1.6.7.1 created 1972, deleted 1978 1.6.7.2 created 1972, deleted 1978 1.6.7.3 created 1978, deleted 1978 1.14.99.5 created 1972, modified 1986, modified 2000, deleted 2000 1.14.99.6 created 1972, modified 2000, deleted 2000 1.14.99.8 created 1972, deleted 1984 1.14.99.13 created 1972, deleted 1984 1.14.99.16 created 1972, deleted 2002 1.14.99.17 created 1972, deleted 1976 1.14.99.18 created 1976, modified 1999, deleted 2003 1.14.99.25 created 1986, deleted 2000
