Partially purified rat liver Δ5-3-ketosteroid isomerase (EC 22.214.171.124) is profoundly and specifically activated by reduced glutathione (GSH). This stimulating effect shows normal saturating kinetics, and both Km and Vmax are pH-dependent. The binding of GSH is independent of the concentration of Δ5-androstene-3,17-dione, whereas the Km for Δ5-androstene-3,17-dione is markedly reduced by saturating levels of GSH. The same catalytic site appears to isomerize both Δ5-androstene-3,17-dione and Δ5-pregnene-3,20-dione. Several steroidal inhibitors compete with Δ5-androstene-3,17-dione, whereas S-methyl-glutathione competes with GSH. This activation of Δ5-3-ketosteroid isomerase is also observed in the livers of other species (calf, guinea pig, human), and represents a hitherto unrecognized function of reduced glutathione.
|Original language||English (US)|
|Number of pages||7|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Apr 19 1976|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology