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EC 1.14.19.21 Details

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EC number

1.14.19.21

Accepted name

cholesterol 7-desaturase

Reaction

cholesterol + O₂ + NAD(P)H + H⁺ = cholesta-5,7-dien-3β-ol + NAD(P)⁺ + 2 H₂O

Other name(s)

nvd (gene name), daf-36 (gene name)

Systematic name

cholesterol,NAD(P)H:oxygen oxidoreductase (7,8 dehydrogenating)

Comment

The enzyme, characterized from several organisms including the worm Caenorhabditis elegans, the fly Drosophila melanogaster, and the ciliate Tetrahymena thermophila, is a Rieske oxygenase. In insects it participates in the the biosythesis of ecdysteroid hormones. The electrons are transferred from NAD(P)H via an electron transfer chain likely to include ferredoxin reductase and ferredoxin. The enzyme differs from regular desaturases, such as EC 1.14.19.20, 7-sterol 5(6)-desaturase, which are cytochrome b₅-dependent and contain the three His-boxes that are typical to most desaturases.

History

created 2015

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

1.4 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

1.6.1 With NAD⁺ or NADP⁺ as acceptor

1.6.2 With a heme protein as acceptor

1.6.3 With oxygen as acceptor

1.6.4 With a disulfide as acceptor (deleted sub-subclass)

1.6.5 With a quinone or similar compound as acceptor

1.6.6 With a nitrogenous group as acceptor

1.6.7 With an iron-sulfur protein as acceptor (deleted sub-subclass)

1.6.8 With a flavin as acceptor (deleted sub-subclass)

1.6.99 With unknown physiological acceptors

1.6.99.1 NADPH dehydrogenase

1.6.99.2 created 1961 as EC 1.6.5.2, transferred 1965 to EC 1.6.99.2, deleted 2005

1.6.99.3 NADH dehydrogenase

1.6.99.4 created 1965, deleted 1972

1.6.99.5 NADH dehydrogenase (quinone)

1.6.99.6 NADPH dehydrogenase (quinone)

1.6.99.7 created 1972, modified 1981 (EC 1.6.99.10 created 1978, incorporated 1981), deleted 2003

1.6.99.8 created 1972, deleted 2002

1.6.99.9 created 1972, deleted 2002

1.6.99.10 created 1978, deleted 1981

1.6.99.11 created 1989, deleted 2002

1.6.99.12 created 1989, deleted 2002

1.6.99.13 created 1992, deleted 2002

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

1.16 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

1.21.99.1 β-cyclopiazonate dehydrogenase

1.21.99.2 cyclic dehypoxanthinyl futalosine synthase

1.21.99.3 thyroxine 5-deiodinase

1.21.99.4 thyroxine 5′-deiodinase

1.21.99.5 tetrachloroethene reductive dehalogenase

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)

1.99 Other enzymes using O₂ as oxidant (deleted subclass)