Effects of adrenal steroid activator protein on the conversion of various 20- and 22-hydroxycholesterols to pregnenolone by adrenal mitochondrial enzymes

Beverly A. Teicher, Mikio Shikita, Paul Talalay

Research output: Contribution to journalArticlepeer-review

Abstract

A heat-stable protein activator from bovine adrenal cortex mitochondria stimulates the conversion of cholesterol to pregnenolone in crude extracts of adrenal mitochondria, and resembles in some of its properties, the sterol carrier protein of liver (Kan et al. Biochem. Biophys. Res. Commun. 48, 423-429, 1972). We have shown that activator preparations also stimulate highly purified adrenal enzyme preparations comprising four components: cytochrome P-450 specific for side chain cleavage, adrenodoxin, adrenodoxin reductase, and an NADPH-generating system. Furthermore, this activator stimulates the conversion not only of cholesterol, but also of (20S)-20-hydroxycholesterol, (22R)-22-hydroxycholesterol, and (20R, 22R)-20,22-dihydroxycholesterol to pregnenolone. Our findings provide additional evidence that the steroid-activator complexes are the substrates for the side chain cleavage enzyme and that the monohydroxy and dihydroxycholesterols are true intermediates in the conversion of cholesterol to pregnenolone by bovine adrenal cortex mitochondria.

Original languageEnglish (US)
Pages (from-to)1436-1441
Number of pages6
JournalBiochemical and Biophysical Research Communications
Volume83
Issue number4
DOIs
StatePublished - Aug 29 1978

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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