Immunochemical comparison of UDP-glucuronyltransferase from Gunn- and Wistar-rat livers.

1. Antiserum was raised against purified Wistar-rat liver UDP-glucuronyltransferase. 2. UDP-glucuronyltransferase activities towards 4-nitrophenol, bilirubin, 1-naphthol and morphine were co-immunoprecipitated from solubilized Wistar-rat liver preparations. 3. UDP-glucuronyltransferase activities towards 1-naphthol, 2-aminophenol and 4-nitrophenol were precipitated from solubilized Gunn-rat liver preparations by this antiserum. 4. UDP-glucuronyltransferase activities towards 1-naphthol, 4-nitrophenol and bilirubin, from Wistar-rat liver, were slightly inhibited by antiserum, whereas 1-naphthol UDP-glucuronyltransferase activity from Gunn-rat livers was greatly inhibited. 5. Measurable Wistar-rat liver glucuronyltransferase activities in washed immunoprecipitates indicate that the enzyme(s) were not merely inhibited by antiserum. 6. Immunoglobulin G purified from this antiserum immunoprecipitated transferase activities towards 4-nitrophenol, bilirubin and 1-naphthol. 7. The washed immunoprecipitates from both rat strains, containing UDP-glucuronyltransferase activity, appear to be similar when analysed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. 8. Radial-immunodiffusion studies suggest that a smaller amount of UDP-glucuronyltransferase protein is present in Gunn-rat liver than in Wistar-rat liver. 9. The significance of these results in relation to the genetic deficiency in the Gunn rat is discussed.