PT - JOURNAL ARTICLE AU - Tzu-Wen Shih AU - Tsu-Han Lin AU - Y. Fulmer Shealy AU - Donald L. Hill TI - Nonenzymatic Isomerization of 9-<em>CIS</em>-Retinoic Acid Catalyzed by Sulfhydryl Compounds DP - 1997 Jan 01 TA - Drug Metabolism and Disposition PG - 27--32 VI - 25 IP - 1 4099 - http://dmd.aspetjournals.org/content/25/1/27.short 4100 - http://dmd.aspetjournals.org/content/25/1/27.full SO - Drug Metab Dispos1997 Jan 01; 25 AB - Certain thiol-containing compounds catalyze, in a chemical reaction, the isomerization of 9-cis-retinoic acid to a mixture of all-trans-retinoic acid, 9-cis-retinoic acid, 13-cis-retinoic acid, and 9,13-dicis-retinoic acid. In the presence of such catalysts, all-trans-retinoic acid gives rise to the same mixture. Reactions approaching equilibrium contain more all-trans-retinoic acid than either of the other isomers. Small molecules effective as catalysts are mercaptoethanol,l-cysteine methyl ester, glutathione, andN-acetyl-l-cysteine. Apoferritin (a thiol-containing protein), native microsomes, and, to a lesser extent, boiled microsomes catalyze the reaction. In intact cells, these interconversions also occur in a process inhibited by a sulfhydryl-specific reagent. The thiol-catalyzed isomerization of 9-cis-retinoic acid may be relevant in the biological activity of this compound. The American Society for Pharmacology and Experimental Therapeutics