Adrenodoxin reductase

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Adrenodoxin reductase (AR) is an FAD containing flavoprotein that function as an electron transfer protein in the mitochondrial P450 systems that catalyze essential steps in biosynthesis of steroid hormones.<ref name="HI-review">PMID:22217824</ref> Its enzyme nomenclature code is [http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/18/1/6.html 1.18.1.6].
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Adrenodoxin reductase (AR) is an FAD containing flavoprotein that functions as an electron transfer protein in the mitochondrial P450 systems that catalyze essential steps in the biosynthesis of steroid hormones.<ref name="HI-review">PMID:22217824</ref>
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The enzyme nomenclature code of AR is [http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/18/1/6.html 1.18.1.6].
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==Mitochondrial P450 systems==
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Mitochondrial P450 systems are composed of three proteins:
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* Adrenodoxin reductase
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* Adrenodoxin, a [2Fe-2S] ferredoxin type iron-sulfur protein
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* Mitochondrial P450
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The reactions catalyzed by P450 type enzymes are called monooxygenation reactions because P450 catalyzes incorporation of only one atom of molecular O<sub>2</sub> into substrate (S) while reducing the second atom of O into H<sub>2</sub>O with the following stoichiometry:
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SH + O<sub>2</sub> + NAD(P)H + H<sup>+</sup>  &rarr;  ROH + H<sub>2</sub>O + NAD(P)<sup>+</sup>
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In the mitochondrial P450 systems, the source of electrons is NADPH. The main function of AR in these systems is to accept two electrons from NADPH and to transfer them one at time to adrenodoxin. Reduced adrenodoxin in turn reduces mitochondrial P450s that catalyze essential steps in the biosynthesis of steroids, such as cleavage of the side chain of cholesterol producing pregnenolone, and C11- and C18 hydroxylation steroids producing cortisol and aldosterone.<ref name="HI-review" />
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==History==
==References==
==References==

Revision as of 18:41, 4 June 2015

Adrenodoxin reductase (AR) is an FAD containing flavoprotein that functions as an electron transfer protein in the mitochondrial P450 systems that catalyze essential steps in the biosynthesis of steroid hormones.[1]

The enzyme nomenclature code of AR is 1.18.1.6.

Contents

Mitochondrial P450 systems

Mitochondrial P450 systems are composed of three proteins:

  • Adrenodoxin reductase
  • Adrenodoxin, a [2Fe-2S] ferredoxin type iron-sulfur protein
  • Mitochondrial P450

The reactions catalyzed by P450 type enzymes are called monooxygenation reactions because P450 catalyzes incorporation of only one atom of molecular O2 into substrate (S) while reducing the second atom of O into H2O with the following stoichiometry:

SH + O2 + NAD(P)H + H+  →  ROH + H2O + NAD(P)+

In the mitochondrial P450 systems, the source of electrons is NADPH. The main function of AR in these systems is to accept two electrons from NADPH and to transfer them one at time to adrenodoxin. Reduced adrenodoxin in turn reduces mitochondrial P450s that catalyze essential steps in the biosynthesis of steroids, such as cleavage of the side chain of cholesterol producing pregnenolone, and C11- and C18 hydroxylation steroids producing cortisol and aldosterone.[1]

History

References

  1. ↑ 1.0 1.1 Hanukoglu I. Steroidogenic enzymes: structure, function, and role in regulation of steroid hormone biosynthesis. J Steroid Biochem Mol Biol. 1992 Dec;43(8):779-804. doi:, 10.1016/0960-0760(92)90307-5. PMID:22217824 doi:http://dx.doi.org/10.1016/0960-0760(92)90307-5

See Also

Adrenodoxin reductase 3D structures

Proteopedia Page Contributors and Editors (what is this?)

Alexander Berchansky, Israel Hanukoglu, Michal Harel, Joel L. Sussman

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