Tritium release from (19-/sup 3/H)-19,19-difluoroandrost-4-ene-3,17-dione during inactivation of aromatase

Conference · Thu May 01 04:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:6992162

Furth, P S; Robinson, C H

Aromatase is a cytochrome P-450 enzyme involved in the conversion of 4-androstene-3,17-dione to estrogen via sequential oxidations at the 19-methyl group. Previous studies from this laboratory have shown that 19,19-difluoro-4-androstene-3,17-dione (1) is a mechanism-based inactivator of aromatase, with Ki=1..mu..M. The mechanism of inactivation was postulated to involve enzymic oxidation at, and hydrogen loss from the 19-carbon. To test this proposal, (19-/sup 3/H)-19,19-difluoro-4-androstene-3,17-dione (2) with specific activity of 34 mCi/mmole, was synthesized to study the release of tritium into solution during the enzyme inactivation process. Incubation of (19-/sup 3/H)-19,19-difluoro-4-androstene-3,17-dione (11..mu..M) with human term placental microsomal aromatase at protein concentrations of 327 to 654..mu..g enzyme protein/ml resulted in time-dependent and protein concentration dependent release of tritium. Similar experiments in which enzyme protein, cofactor or both were omitted served as the controls for these studies.

• Research Organization: Johns Hopkins Univ. School of Medicine, Baltimore, MD
• OSTI ID: 6992162
• Report Number(s): CONF-8606151-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANDROGENS
ANDROSTANES
ANDROSTENEDIONE
ANIMALS
BIOSYNTHESIS
ENZYME ACTIVITY
ENZYMES
ESTROGENS
FETAL MEMBRANES
HORMONES
ISOMERASES
ISOTOPE APPLICATIONS
KETONES
LABELLED COMPOUNDS
MAMMALS
MAN
MEMBRANES
METABOLISM
ORGANIC COMPOUNDS
PLACENTA
PRIMATES
STEROID HORMONES
STEROIDS
SYNTHESIS
TIME DEPENDENCE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES