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EC 1.14.12.20 Details

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EC number

1.14.12.20

Accepted name

pheophorbide a oxygenase

Reaction

pheophorbide a + NADPH + H⁺ + O₂ = red chlorophyll catabolite + NADP⁺

Other name(s)

pheide a monooxygenase, pheide a oxygenase, PaO, PAO

Systematic name

pheophorbide-a,NADPH: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, deleted 2016

EC Tree

1 Oxidoreductases

1.1 Acting on the CH-OH group of donors

1.2 Acting on the aldehyde or oxo group of donors

1.3 Acting on the CH-CH group of donors

1.3.1 With NAD⁺ or NADP⁺ as acceptor

1.3.2 With a cytochrome as acceptor

1.3.3 With oxygen as acceptor

1.3.4 With a disulfide as acceptor

1.3.5 With a quinone or related compound as acceptor

1.3.7 With an iron-sulfur protein as acceptor

1.3.7.1 6-hydroxynicotinate reductase

1.3.7.2 15,16-dihydrobiliverdin:ferredoxin oxidoreductase

1.3.7.3 phycoerythrobilin:ferredoxin oxidoreductase

1.3.7.4 phytochromobilin:ferredoxin oxidoreductase

1.3.7.5 phycocyanobilin:ferredoxin oxidoreductase

1.3.7.6 phycoerythrobilin synthase

1.3.7.7 ferredoxin:protochlorophyllide reductase (ATP-dependent)

1.3.7.8 benzoyl-CoA reductase

1.3.7.9 4-hydroxybenzoyl-CoA reductase

1.3.7.10 pentalenolactone synthase

1.3.7.11 2,3-bis-O-geranylgeranyl-sn-glycero-phospholipid reductase

1.3.7.12 red chlorophyll catabolite reductase

1.3.7.13 3,8-divinyl protochlorophyllide a 8-vinyl-reductase (ferredoxin)

1.3.7.14 3,8-divinyl chlorophyllide a reductase

1.3.7.15 chlorophyllide a reductase

1.3.8 With a flavin as acceptor

1.3.98 With other, known, physiological acceptors

1.3.99 With unknown physiological acceptors

1.4 Acting on the CH-NH₂ group of donors

1.5 Acting on the CH-NH group of donors

1.6 Acting on NADH or NADPH

1.7 Acting on other nitrogenous compounds as donors

1.8 Acting on a sulfur group of donors

1.9 Acting on a heme group of donors

1.10 Acting on diphenols and related substances as donors

1.11 Acting on a peroxide as acceptor

1.12 Acting on hydrogen as donor

1.13 Acting on single donors with incorporation of molecular oxygen (oxygenases)

1.14 Acting on paired donors, with incorporation or reduction of molecular oxygen

1.15 Acting on superoxide as acceptor

1.15.1 Acting on superoxide as acceptor (only sub-subclass identified to date)

1.16 Oxidizing metal ions

1.17 Acting on CH or CH₂ groups

1.18 Acting on iron-sulfur proteins as donors

1.19 Acting on reduced flavodoxin as donor

1.20 Acting on phosphorus or arsenic in donors

1.21 Catalysing the reaction X-H + Y-H = X-Y

1.21.1 With NAD⁺ or NADP⁺ as acceptor

1.21.3 With oxygen as acceptor

1.21.4 With a disulfide as acceptor

1.21.98 With other, known, physiological acceptors

1.21.99 With unknown physiological acceptors

1.22 Acting on halogen in donors

1.23 Reducing C-O-C group as acceptor

1.97 Other oxidoreductases

1.97.1 Sole sub-subclass for oxidoreductases that do not belong in the other subclasses

1.98 Enzymes using H₂ as reductant (deleted subclass)

1.98.1. undefined

1.99 Other enzymes using O₂ as oxidant (deleted subclass)

3.1 Acting on ester bonds

3.2 Glycosylases

3.3 Acting on ether bonds

3.4 Acting on peptide bonds (peptidases)

3.5 Acting on carbon-nitrogen bonds, other than peptide bonds

3.6 Acting on acid anhydrides

3.6.1 In phosphorus-containing anhydrides

3.6.2 In sulfonyl-containing anhydrides

3.6.3 Acting on acid anhydrides to catalyse transmembrane movement of substances

3.6.4 Acting on acid anhydrides to facilitate cellular and subcellular movement

3.6.5 Acting on GTP to facilitate cellular and subcellular movement

3.7 Acting on carbon-carbon bonds

3.8 Acting on halide bonds

3.9 Acting on phosphorus-nitrogen bonds

3.10 Acting on sulfur-nitrogen bonds

3.11 Acting on carbon-phosphorus bonds

3.12 Acting on sulfur-sulfur bonds

3.13 Acting on carbon-sulfur bonds

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Release 2023.1 (January 2023)