EFFECTS OF FATTY-ACIDS AND FATTY ACYL COA ESTERS ON CU2+-INDUCED CONVERSION OF XANTHINE DEHYDROGENASE TO OXIDASE IN RABBIT LIVER

Effects of various fatty acids and fatty acyl CoA esters on Cu2+-induced conversion of xanthine dehydrogenase to oxidase in rabbit liver were examined. Cu2+ (2-10 mu M) brought about the conversion of xanthine dehydrogenase to oxidase in a dose-dependent manner. Oleic, arachidonic, eicosapentaenoic, and docosahexaenoic acids (50-200 mu M) prevented the conversion of xanthine dehydrogenase to oxidase catalyzed by 6 mu M-Cu2+. The effect of these four fatty acids was concentration-dependent, whereas palmitic, stearic, and linoleic acids had no effect on the conversion of xanthine dehydrogenase to oxidase at the same concentration range. On the other hand, palmitoyl, linoleoyl, and arachidonoyl CoAs elicited the inhibition of 6 mu M-Cu2+-induced conversion of xanthine dehydrogenase to oxidase at concentrations of 50, 100, and 200 mu M. These results suggest that oleic, arachidonic, eicosapentaenoic and docosahexaenoic acids, and fatty acyl CoAs have the potential to inhibit the conversion of xanthine dehydrogenase to oxidase in rabbit liver.