KEGG   ENZYME: 1.14.13.122Help
Entry
EC 1.14.13.122              Enzyme                                 

Name
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
BRITE hierarchy
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]
Reaction(KEGG)
Substrate
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
Pathway
Porphyrin and chlorophyll metabolism
Metabolic pathways
Biosynthesis of secondary metabolites
Orthology
K13600  
chlorophyllide a oxygenase
Genes
ATH: 
ALY: 
CRB: 
EUS: 
BRP: 
BNA: 
THJ: 
CIT: 
CIC: 
TCC: 
GRA: 
EGR: 
GMX: 
PVU: 
VRA: 
VAR: 
MTR: 
CAM: 
ADU: 
AIP: 
LJA: 
Lj0g3v0362219.1(Lj0g3v0362219.1)
LANG: 
FVE: 
PPER: 
PMUM: 
MDM: 
PXB: 
CSV: 
101205768(CSCAO)
CMO: 
RCU: 
JCU: 
POP: 
POPTR_0002s08380g(POPTRDRAFT_1071581) POPTR_0005s20060g(POPTRDRAFT_716668)
VVI: 
SLY: 
SPEN: 
SOT: 
INI: 
SIND: 
BVG: 
NNU: 
OSA: 
DOSA: 
Os10t0567100-01(Os10g0567100) Os10t0567400-01(Os10g0567400)
OBR: 
BDI: 
ATS: 
SBI: 
SORBI_03g046660(SORBIDRAFT_03g046660)
ZMA: 
100274228 100284976(pco079065e)
SITA: 
PDA: 
EGU: 
MUS: 
ATR: 
SMO: 
PPP: 
CRE: 
VCN: 
OLU: 
OTA: 
BPG: 
MIS: 
MPP: 
CSL: 
CVR: 
APRO: 
ACAN: 
 » show all
Taxonomy
Reference
1  [PMID:10468639]
  Authors
Espineda CE, Linford AS, Devine D, Brusslan JA.
  Title
The AtCAO gene, encoding chlorophyll a oxygenase, is required for chlorophyll b synthesis in Arabidopsis thaliana.
  Journal
Proc. Natl. Acad. Sci. U. S. A. 96 (1999) 10507-11.
  Sequence
[ath:AT1G44446]
Reference
2  [PMID:10758481]
  Authors
Oster U, Tanaka R, Tanaka A, Rudiger W.
  Title
Cloning and functional expression of the gene encoding the key enzyme for chlorophyll b biosynthesis (CAO) from Arabidopsis thaliana.
  Journal
Plant. J. 21 (2000) 305-10.
  Sequence
[ath:AT1G44446]
Reference
3  [PMID:15086960]
  Authors
Eggink LL, LoBrutto R, Brune DC, Brusslan J, Yamasato A, Tanaka A, Hoober JK.
  Title
Synthesis of chlorophyll b: localization of chlorophyllide a oxygenase and discovery of a stable radical in the catalytic subunit.
  Journal
BMC. Plant. Biol. 4 (2004) 5.
  Sequence
Reference
4  [PMID:8307032]
  Authors
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.
  Journal
Eur. J. Biochem. 219 (1994) 671-9.
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 
CAS: 
216503-73-0

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