Isolation from bovine liver mitochondria of a soluble ferredoxin active in a reconstituted steroid hydroxylation reaction. |
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Authors: | Jan I Pedersen Helge Oftebro Tore Vänngård |
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Institution: | 1. Institute for Nutrition Research, School of Medicine, University of Oslo, Oslo, Norway;2. Department of Biochemistry, Chalmers Institute of Technology and University of Göteborg, Göteborg, Sweden |
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Abstract: | An iron-sulfur protein has been isolated from bovine liver mitochondria and purified 140-fold on DEAE-cellulose and Sephadex G-100. During the isolation the protein was detected by its NADPH-cytochrome reductase activity in the presence of adrenal NADPH-ferredoxin reductase. The molecular weight of the protein (12,400), the optical spectrum (peaks at 414 nm and 455 nm which disappear upon reduction), and the EPR spectrum (gx = gy = 1.935 and gz = 2.02) were typical for a ferredoxin. In the presence of soluble adrenal cytochrome P450, ferredoxin reductase and NADPH, this protein could support the formation of pregnenolone from cholesterol. Under similar conditions, but in the presence of a cytochrome P450 solubilized from rat liver mitochondria, cholesterol was transformed into a more polar compound tentatively identified as 26-hydroxycholesterol. |
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