The final step of aldosterone biosynthesis is catalyzed by an NADPH-dependent and molecular oxygen-requiring enzyme |
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Authors: | Itaru Kojima Hiroshi Inano Bun-ichi Tamaoki |
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Institution: | National Institute of Radiological Sciences, Anagawa-4-chome, Chiba-shi 260, Japan |
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Abstract: | Using sonicated mitochondria fraction prepared from bovine adrenal glomerulosa cells, aldosterone biosynthesis from 18-hydroxycorticosterone was examined as its final step, as production of 3H]-aldosterone from 3H]-corticosterone was strongly reduced by addition of non-radioactive 18-hydroxycorticosterone during the incubation. Significant conversion of 18-hydroxycorticosterone to aldosterone by the mitochondria sonicate was observed in the presence of NADPH, but not NADP+. This reaction was almost completely inhibited in the atmosphere of 100% carbon monoxide in the presence of either NADP+, or NAD+, and significantly reduced in the mixture of carbon monoxide and oxygen (90:10) in the presence of NADPH. Several drugs, such as SU compounds, spironolactone, amphenone B and SKF 525A which affect cytochrome P-450 blocked production of aldosterone from 18-hydroxycorticosterone. From these results, we conclude that a mixed function oxidase involving a cytochrome P-450 is engaged in the final course of aldosterone biosynthesis. |
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Keywords: | To whom requests for reprints should be addressed |
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