Metabolism of Drugs. XLIII. Comparison of Glucuronyl Transfer Activity between β-Glucuronidase and Uridine Diphosphate Transglucuronylase.

1. UDP-transglucuronylase catalyzed the transfer of the glucuronyl group from UDP glucuronic acid to phenolic compounds, such as 2-naphthol, p-cresol, p-nitrophenol, m-aminophenol, and p-aminosalicylic acid, but the glucuronyl transfer by β-glucuronidase from phenolphthalein β-D-glucuronide or p-nitrophenyl β-D-glucuronide to these phenolic compounds was not observed. 2. The transfer product by β-glucuronidase from p-nitrophenyl β-D-glucuronide to methanol was identified by paper chromatography, and percentage of glucuronyl transfer activity was also measured. This glucuronide transferred 24.2 per cent of the liberated glucuronic group to methanol.