Metabolism of Drugs. XLIV. Glucuronyl Transfer Reaction catalyzed by β-Glucuronidase by the Use of Ester Glucuronides as Substrates.

1. The glucuronyl transfer reaction from ester glucuronides to aliphatic alcohols were examined with partially purified rabbit liver β-glucuronidase and E. coli β-glucuronidase. The enzymes transferred the glucuronic acid moiety of ester glucuronides to aliphatic alcohols. The product with methanol was identified to be methyl glucuronide by paper chromatography. The product was completely hydrolyzable by β-glucuronidase, proving it to be a β-glucosiduronic acid of methanol. 2. The glucuronyl transfer from ester glucuronides to m-aminophenol was examined. The product formed by glucuronyl transfer from benzoyl β-D-glucuronide to m-aminophenol was purified with ion exchange resin. It contained equimolar amounts of m-aminophenol and glucuronic acid. The paper electrophoretic and paper chromatographic behavior of this purified product was presented. In paper chromatography, the Rf value of this product was different from that of authentic m-aminophenyl β-D-glucuronide. This product was not hydrolyzable by β-glucuronidase and more stable in acidic milieu than authentic m-aminophenyl β-D-glucuronide. These facts suggested the presence of α-glucosiduronic linkage in its molecule.