Role of reduced glutathione in the Δ5-3-ketosteroid isomerase reaction of liver

Ann M. Benson, Paul Talalay

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Partially purified rat liver Δ5-3-ketosteroid isomerase (EC 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 languageEnglish (US)
Pages (from-to)1073-1079
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number4
StatePublished - Apr 19 1976

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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