Corticosteroid side chain oxidations--3. Evidence for isomerization and direct oxidation reactions in the formation of steroid 21-oic acids by rabbit liver cytosol.
Isomerase complexes that oxidize the alpha-ketol side chain of deoxycorticosterone (DOC) to pregnolic and pregnenoic acids without the addition of cofactors have been purified from rabbit and hamster liver cytosols. The isomerase complex in rabbit liver cytosol was partially resolved from a NAD-dependent dehydrogenase that oxidized the glycol side chain of 20 beta-dihydro DOC to the 20 beta-hydroxy-21-oic acid. Corticosterone (B) and 20 beta-dihydro B were less active substrates than DOC or 20 beta-dihydro DOC with the corresponding preparations. The rabbit resembles other rodent and human species in that isomerization and oxidation at C21 is the major pathway of acid formation whereas direct oxidation at C21 may only be of significance with metabolites that have the glycol side chain.
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Medical School, Memorial University of Newfoundland, St John's, Canada.
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D000305:Adrenal Cortex Hormones / Q000378:metabolism*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D003600:Cytosol / Q000201:enzymology; D003900:Desoxycorticosterone / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007535:Isomerases / Q000302:isolation & purification / Q000378:metabolism*; D008099:Liver / Q000201:enzymology* / Q000648:ultrastructure; D009243:NAD / Q000494:pharmacology; D009249:NADP / Q000494:pharmacology; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D011283:Pregnenes / Q000378:metabolism*; D011817:Rabbits; D013347:Subcellular Fractions / Q000201:enzymology; D013379:Substrate Specificity
D000305:Adrenal Cortex Hormones; D011283:Pregnenes; D009243:NAD; C035466:20-hydroxy-3-oxo-4-pregnen-21-carboxylic acid; C080522:11,20-dihydroxy-4-pregnene-3-one-21-oic acid; D003900:Desoxycorticosterone; D009249:NADP; D010088:Oxidoreductases; D007535:Isomerases