Biochemical mechanism of aromatization

Cancer Res. 1982 Aug;42(8 Suppl):3277s-3280s.


The aromatization of androgens to estrogens by placental aromatase involves three hydroxylations which take place in sequence. The first two occur at the C-19-methyl group while the site of the final and rate-determining hydroxylation has been identified as being at 2 beta. The product of this reaction collapses to estrogen by a rapid nonenzymatic mechanism. The absence of a direct relationship between the enzyme(s) responsible for estrogen formation and the end product results in an absence of product feedback inhibition, a consequence with potential physiological implications. The proposed mechanism of estrogen formation is supported by chemical, biochemical, and immunological evidence.

MeSH terms

  • Aromatase / metabolism*
  • Chemical Phenomena
  • Chemistry
  • Estrogens / biosynthesis*
  • Female
  • Humans
  • Hydroxylation
  • Oxidoreductases / metabolism*
  • Placenta / enzymology*
  • Pregnancy


  • Estrogens
  • Oxidoreductases
  • Aromatase