Carotenoids are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria, archaea, and fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, corn, tomatoes, canaries, flamingos, salmon, lobster, shrimp, and daffodils. Over 1,100 identified carotenoids can be further categorized into two classes – xanthophylls and carotenes.
CRT is the gene cluster responsible for the biosynthesis of carotenoids. Those genes are found in eubacteria, in algae and are cryptic in Streptomyces griseus.
In enzymology, a carotene 7,8-desaturase (EC 1.14.99.30) is an enzyme that catalyzes the chemical reaction
The enzyme 4-oxalmesaconate hydratase (EC 4.2.1.83) catalyzes the chemical reaction
9,9'-dicis-zeta-carotene desaturase is an enzyme with systematic name 9,9'-dicis-zeta-corotene:quinone oxidoreductase. This enzyme catalyses the following chemical reaction
All-trans-zeta-carotene desaturase is an enzyme with systematic name all-trans-zeta-carotene:acceptor oxidoreductase. This enzyme catalyses the following chemical reaction
1-Hydroxycarotenoid 3,4-desaturase is an enzyme with systematic name 1-hydroxy-1,2-dihydrolycopene:acceptor oxidoreductase. This enzyme catalyses the following chemical reaction
Phytoene desaturase (neurosporene-forming) is an enzyme with systematic name 15-cis-phytoene:acceptor oxidoreductase (neurosporene-forming). This enzyme catalyses the following chemical reaction
Phytoene desaturase (zeta-carotene-forming) is an enzyme with systematic name 15-cis-phytoene:acceptor oxidoreductase (zeta-carotene-forming). This enzyme catalyses the following chemical reaction
Phytoene desaturase (lycopene-forming) are enzymes found in archaea, bacteria and fungi that are involved in carotenoid biosynthesis. They catalyze the conversion of colorless 15-cis-phytoene into a bright red lycopene in a biochemical pathway called the poly-trans pathway. The same process in plants and cyanobacteria utilizes four separate enzymes in a poly-cis pathway.
Magnesium-protoporphyrin IX monomethyl ester (oxidative) cyclase, is an enzyme with systematic name magnesium-protoporphyrin-IX 13-monomethyl ester, ferredoxin:oxygen oxidoreductase (hydroxylating). In plants this enzyme catalyses the following overall chemical reaction
Monocyclic monoterpene ketone monooxygenase (EC 1.14.13.105, 1-hydroxy-2-oxolimonene 1,2-monooxygenase, dihydrocarvone 1,2-monooxygenase, MMKMO) is an enzyme with systematic name (-)-menthone,NADPH:oxygen oxidoreductase. This enzyme catalyses the following chemical reaction
Beta-carotene 3-hydroxylase (EC 1.14.13.129, beta-carotene 3,3'-monooxygenase, CrtZ) is an enzyme with systematic name beta-carotene,NADH:oxygen 3-oxidoreductase . This enzyme catalyses the following chemical reaction
Spheroidene monooxygenase (EC 1.14.15.9, CrtA, acyclic carotenoid 2-ketolase, spirilloxantin monooxygenase, 2-oxo-spirilloxanthin monooxygenase) is an enzyme with systematic name spheroidene, reduced-ferredoxin:oxygen oxidoreductase (spheroiden-2-one-forming). This enzyme catalyses the following chemical reaction
Demethylspheroidene O-methyltransferase is an enzyme with systematic name S-adenosyl-L-methionine:demethylspheroidene O-methyltransferase. This enzyme catalyses the following chemical reaction
4,4'-diapophytoene synthase is an enzyme with systematic name farnesyl-diphosphate:farnesyl-diphosphate farnesyltransferase . This enzyme catalyses the following chemical reaction
2-hydroxyhexa-2,4-dienoate hydratase (EC 4.2.1.132, tesE (gene), hsaE (gene)) is an enzyme with systematic name 4-hydroxy-2-oxohexanoate hydro-lyase ((2Z,4Z)-2-hydroxyhexa-2,4-dienoate-forming). This enzyme catalyses the following chemical reaction
Lycopene ε-cyclase is an enzyme with systematic name carotenoid psi-end group lyase (decyclizing). This enzyme catalyses the following chemical reaction
Lycopene β-cyclase is an enzyme with systematic name carotenoid beta-end group lyase (decyclizing). This enzyme catalyses the following chemical reaction
Chlorophyllide a and Chlorophyllide b are the biosynthetic precursors of chlorophyll a and chlorophyll b respectively. Their propionic acid groups are converted to phytyl esters by the enzyme chlorophyll synthase in the final step of the pathway. Thus the main interest in these chemical compounds has been in the study of chlorophyll biosynthesis in plants, algae and cyanobacteria. Chlorophyllide a is also an intermediate in the biosynthesis of bacteriochlorophylls.
