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. 2019 Jul 12;294(28):10743-10745.
doi: 10.1074/jbc.CL119.009620. Epub 2019 Jul 12.

On the trail of steroid aromatase: The work of Kenneth J. Ryan

Martin J Spiering

On the trail of steroid aromatase: The work of Kenneth J. Ryan

Martin J Spiering. J Biol Chem. .
No abstract available

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Figures

Figure 1.
Figure 1.
Steroid aromatase (estrogen synthase) is a cytochrome P450 enzyme that aromatizes androgens to estrogens. Kenneth Ryan developed a protocol for improved extraction of steroid aromatase activity from human placentas (2). This improvement opened up the way for later in-depth studies of this enzyme, revealing that steroid aromatase is a P450 monooxygenase that catalyzes three reactions (indicated by boxed numbers above/beside the 1st three arrows) in the conversion of androgens such as testosterone to estrogens such as estradiol. These reactions include two hydroxylations at carbon 19 and an uncommon third oxidation step leading to multiple molecular rearrangements (10), resulting in carbon 19 elimination, reduction of the A-ring keto group to a hydroxyl, and A-ring aromatization.
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References

    1. Ryan K. J., and Engel L. L. (1957) Hydroxylation of steroids at carbon 21. J. Biol. Chem. 225, 103–114 http://www.jbc.org/content/225/1/103.long - PubMed
    1. Ryan K. J. (1959) Biological aromatization of steroids. J. Biol. Chem. 234, 268–272 http://www.jbc.org/content/234/2/268.long - PubMed
    1. Ryan K. J. (1959) Metabolism of C-16–oxygenated steroids by human placenta: the formation of estriol. J. Biol. Chem. 234, 2006–2008 http://www.jbc.org/content/234/8/2006.long - PubMed
    1. Steinach E., and Kun H. (1937) Transformation of male sex hormones into a substance with the action of a female hormone. Lancet 133, 845
    1. Meyer A. S. (1955) Conversion of 19-hydroxy-Δ4-androstene-3,17-dione to estrone by endocrine tissue. Biochim. Biophys. Acta 17, 441–442 10.1016/0006-3002(55)90395-4 - DOI - PubMed

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