pheophorbide a oxygenase;
pheide a monooxygenase;
pheide a oxygenase;
PaO;
PAO
Class
Oxidoreductases;
Acting on paired donors, with incorporation or reduction of molecular oxygen;
With reduced iron-sulfur protein as one donor, and incorporation of one atom of oxygen into the other donor
pheophorbide a [CPD:C18021];
reduced ferredoxin [iron-sulfur] cluster [CPD:C00138];
H+ [CPD:C00080];
O2 [CPD:C00007];
epoxypheophorbide a [CPD:C21192];
H2O [CPD:C00001]
Product
red chlorophyll catabolite [CPD:C18022];
oxidized ferredoxin [iron-sulfur] cluster [CPD:C00139];
epoxypheophorbide a [CPD:C21192];
H2O [CPD:C00001]
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
EC 1.14.15.17 created 2007 as EC 1.14.12.20, transferred 2016 to EC 1.14.15.17