• Source: Phytoene desaturase (lycopene-forming)

Phytoene desaturase (lycopene-forming) (CrtI, four-step phytoene desaturase) (EC 1.3.99.31, 15-cis-phytoene:acceptor oxidoreductase (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.




Biochemistry



Bacterial phytoene desaturases were shown to require FAD as a cofactor for their function. During the chemical reaction in total four additional double bonds are introduced into phytoene:

15-cis-phytoene + 4 acceptor



⇌


{\displaystyle \rightleftharpoons }

all-trans-lycopene + 4 reduced acceptor (overall reaction)
(1a) 15-cis-phytoene + acceptor



⇌


{\displaystyle \rightleftharpoons }

all-trans-phytofluene + reduced acceptor
(1b) all-trans-phytofluene + acceptor



⇌


{\displaystyle \rightleftharpoons }

all-trans-zeta-carotene + reduced acceptor
(1c) all-trans-zeta-carotene + acceptor



⇌


{\displaystyle \rightleftharpoons }

all-trans-neurosporene + reduced acceptor:
(1d) all-trans-neurosporene + acceptor



⇌


{\displaystyle \rightleftharpoons }

all-trans-lycopene + reduced acceptor




Applications


In 2000 it was discovered that the gene insertion of a bacterial phytoene desaturase into transgenic tomatoes increased the lycopene content without the need to alter several of the plants enzymes. This approach was later used in rice to increase its β-carotene content resulting in the Golden Rice project.




See also


15-''Cis''-phytoene desaturase
Phytoene desaturase (neurosporene-forming)
Phytoene desaturase (zeta-carotene-forming)
Phytoene desaturase (3,4-didehydrolycopene-forming)




References






External links


Phytoene+desaturase+(lycopene-forming) at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

Kata Kunci Pencarian:

• Phytoene desaturase (lycopene-forming)
• Phytoene desaturase
• Phytoene desaturase (neurosporene-forming)
• Phytoene desaturase (zeta-carotene-forming)
• Phytoene desaturase (3,4-didehydrolycopene-forming)
• 15-Cis-phytoene desaturase
• Golden rice
• Astaxanthin
• Carotenoid
• Damascenone