Biological aromatization of steroids.

  title={Biological aromatization of steroids.},
  author={K. Ryan},
  journal={The Journal of biological chemistry},
  volume={234 2},
  • K. Ryan
  • Published 1959
  • Medicine, Biology
  • The Journal of biological chemistry
The conversion of androgenic steroids to the phenolic estrogens by mammalian tissue has been well documented. The reaction has been reported in relatively low yield, in vitro with ovarian and placental slices (l-3), and in viva after the administration of androgens to various species including man (4, 5). The present report describes the conversion of androgens to estrogens in high yield by a system consisting of human placental microsomes, the reduced form of triphosphopyridine nucleotide, and… Expand
Equine testicular aromatase: substrates specificity and kinetic characteristics.
  • J. Gaillard
  • Biology, Medicine
  • Comparative biochemistry and physiology. B, Comparative biochemistry
  • 1991
The equine testicular enzyme aromatized androgens and 19-norandrogens with similar velocity, but not 16 alpha-hydroxytestosterone or epitestosterone in contrast to the human placental aromatase. Expand
A series of experiments has been conducted in order to determine the stoichiometry of the overall reaction, as well as to investigate further what role, if any, cytochrome P-450 plays in aromatization. Expand
Aromatization of testosterone and 19-nortestosterone by a single enzyme from equine testicular microsomes. Differences from human placental aromatase.
The differences observed suggest that the aromatase in the horse testis is not the same as that in the human placenta, as well as the rate of norandrogen aromatization. Expand
Enzymatic androgen assay: some properties of human placental microsomal aromatase.
Using an accurate, specific and sensitive assay for HPMA, Km values for dehydroepiandrosterone (DHEA), androstenedione and testosterone were found to increase with increasing amount of the detergent added, and kinetic properties of aromatase before and after solubilization are described. Expand
The flux of intermediates and products in aromatizaton of C19 steroids by human placental microsomes.
The appearance of intermediates and products in the transformation of 4- androstene-3,17-dione and testosterone to estrone and 17β-estradiol by human placental microsomes was studied and 17α-Hydroxy-5α-androst-1-en-3-one was found to be an inhibitor of the C19 17 β-hydroxysteroid dehydrogenase activity of human placents. Expand
[37] Enzymes of estrogen metabolism
This chapter attempts to draw together most of the available data relating to estrogen metabolism, and several analytical methods are referred to recurrently throughout the subsequent discussion, these are outlined. Expand
Steroid hormone transformations by endocrine organs from pregnant mammals. VI. The conversion of delta-4-androstene-3,17-dione to estrogens by goat placental preparations in vitro.
The results demonstrate the potential importance of the goat placenta as a source of estrogens during pregnancy and show the conversion of Δ 4 -androstene-3,17-dione-4- 14 C to radioactive estrone, estradiol-17α and estradio-17β has been shown in vitro with goat placental tissue preparations. Expand
Human aromatase: Perspectives in biochemistry and biotechnology
Aromatase (CYP19) is involved in steroidogenesis, catalyzing the conversion of androgens into estrogens through a unique reaction that causes the aromatization of the A ring of the steroid. TheExpand
Inhibition and inactivation of estrogen synthetase (aromatase) by fluorinated substrate analogues.
The interaction of these compounds with the estrogen synthetase (aromatase) activity of human placental microsomes has been studied, and this substrate analogue has been shown to be converted to estrone in high yield by this enzyme system. Expand
Studies on the mechanism of estrogen biosynthesis. V. Stereochemical comparison of aromatization in placental and microbiological systems.
The results show that the transformation of I to estrone in the two types of systems occurs by different stereochemical mechanisms, and that probably different electronic factors are involved also. Expand


hp://w w w D ow nladed from Kenneth J. Ryan Biological Aromatization of Steroids
  • Biochim. et Biophys. Acta,
  • 1958