chlorophyllide-a oxygenase;
chlorophyllide a oxygenase;
chlorophyll-b synthase;
CAO
Class
Oxidoreductases;
Acting on paired donors, with incorporation or reduction of molecular oxygen;
With NADH or NADPH as one donor, and incorporation of one atom of oxygen into the other donor
Sysname
chlorophyllide-a:oxygen 71-oxidoreductase
Reaction(IUBMB)
chlorophyllide a + 2 O2 + 2 NADPH + 2 H+ = chlorophyllide b + 3 H2O + NADP+ (overall reaction) [RN:R10080];
(1a) chlorophyllide a + O2 + NADPH + H+ = 71-hydroxychlorophyllide a + H2O + NADP+ [RN:R08203];
(1b) 71-hydroxychlorophyllide a + O2 + NADPH + H+ = chlorophyllide b + 2 H2O + NADP+ [RN:R08204]
chlorophyllide a [CPD:C02139];
O2 [CPD:C00007];
NADPH [CPD:C00005];
H+ [CPD:C00080];
71-hydroxychlorophyllide a
Product
chlorophyllide b [CPD:C16541];
H2O [CPD:C00001];
NADP+ [CPD:C00006];
71-hydroxychlorophyllide a
Comment
Chlorophyll b is required for the assembly of stable light-harvesting complexes (LHCs) in the chloroplast of green algae, cyanobacteria and plants [2,3]. Contains a mononuclear iron centre [3]. The enzyme catalyses two successive hydroxylations at the 7-methyl group of chlorophyllide a. The second step yields the aldehyde hydrate, which loses H2O spontaneously to form chlorophyllide b [2]. Chlorophyll a and protochlorophyllide a are not substrates [2].
History
EC 1.14.13.122 created 2006 as EC 1.13.12.14, transferred 2011 to EC 1.14.13.122, modified 2011
Porra RJ, Schafer W, Cmiel E, Katheder I, Scheer H.
Title
The derivation of the formyl-group oxygen of chlorophyll b in higher plants from molecular oxygen. Achievement of high enrichment of the 7-formyl-group oxygen from 18O2 in greening maize leaves.
