Studies of human placental aromatase

Pentti K. Siiteri, E Aubrey Thompson

Research output: Contribution to journalArticle

171 Citations (Scopus)

Abstract

Kinetic analysis of aromatization of androstenedione (Δ4) indicates that 3 mol of oxygen and NADPH are consumed in the formation of estrone (El). During the steady state, the 3d oxidation appears to be the rate limiting step since both 19-hydroxy and 19-oxo-androstenedione accumulate prior to El. Cytochrome P-450 participation in each hydroxylation step is suggested by (1) inhibition by known P-450 inhibitors other than CO, (2) inhibition by an antibody to NADPH-cytochrome c reductase, (3) spectral studies of P-450 binding of substrate and intermediates, and (4) solubilization and partial resolution of enzyme components using digitonin and DEAE cellulose. A survey of steroidal compounds has revealed that 5α-reduced androstenedione is a potent competitive inhibitor which may be of physiologic importance in control of ovarian estrogen synthesis. Finally, many steroidal drugs used in treatment of breast cancer are competitive inhibitors. The non androgenic compound 1-ene-testololactone is effective both in vitro and in vivo suggesting that antitumor activity of steroidal drugs may be due to inhibition of estrogen synthesis rather than direct androgen action.

Original languageEnglish (US)
Pages (from-to)317-322
Number of pages6
JournalJournal of Steroid Biochemistry
Volume6
Issue number3-4
DOIs
StatePublished - 1975
Externally publishedYes

Fingerprint

Aromatase
Androstenedione
Androgens
Estrogens
Aromatization
Digitonin
DEAE-Cellulose
NADPH-Ferrihemoprotein Reductase
Hydroxylation
Estrone
Carbon Monoxide
NADP
Pharmaceutical Preparations
Cytochrome P-450 Enzyme System
Breast Neoplasms
Oxygen
Oxidation
Kinetics
Antibodies
Substrates

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology

Cite this

Studies of human placental aromatase. / Siiteri, Pentti K.; Thompson, E Aubrey.

In: Journal of Steroid Biochemistry, Vol. 6, No. 3-4, 1975, p. 317-322.

Research output: Contribution to journalArticle

Siiteri, Pentti K. ; Thompson, E Aubrey. / Studies of human placental aromatase. In: Journal of Steroid Biochemistry. 1975 ; Vol. 6, No. 3-4. pp. 317-322.
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