Abstract
In contrast to previous reports, cis-dihydroaldrindiol, as well as the trans-isomer, has been shown to be formed in vitro from dieldrin in rat liver preparations. Further, an enzyme in the same fraction of rat liver homogenate has been shown to rapidly epimerize synthetic cis-dihydroaldrindiol to the trans-isomer in vitro. The epimerase is located in the microsomes and requires NADPH and cytochrome P-450, but does not require molecular oxygen. Thus, it apparently utilizes a portion of the mixed-function oxidase electron transfer chain, but cannot be considered a mixed-function oxidase. The existence of such an epimerase in close association with the enzyme responsible for the oxidation of cyclic hydrocarbons may explain the stereochemical configuration of the dihydrodiol metabolite of dieldrin, and possibly other cyclic hydrocarbons, excreted by mammals.
Footnotes
- Received November 24, 1973.
- Copyright © 1974 by The American Society for Pharmacology and Experimental Therapeutics
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