Comparative abilities and optimal conditions for β-glycosidase enzymes to hydrolyse the glucuronide, glucoside, and N-acetylglucosaminide conjugates of bile acids

Abstract

Enzymatic hydrolyses were described for three variants of glycosidic conjugated bile acids with one β-glucuronidase (Helix pomatia), three β- glucosidase (almonds, sweet almonds, and Escherichia coli), and four β-N- acetylglucosaminidase (jack beans, bovine kidney; human placenta, and Diplococcus pneumoniae) preparations. The substrates include the β- glucuronide, β-glucoside, and β-N-acetylglucosaminide conjugates of bile acids related to hyodeoxycholic, murideoxycholic, chenodeoxycholic, and ursodeoxycholic acids possessing a sugar moiety at position C-3; C-6 or C-7. The comparative abilities and optimal conditions for the β-glycosidases to catalyze the hydrolyses of the substrates were clarified by changing pHs and incubation times. Hydrolysis rates of the bile acid glycosides with β- glycosidase treatments were influenced by both the source of the enzyme preparations and the conjugated position of a sugar moiety in the substrates, and the 3-glucoside and 3-N-acetylglucosaminide conjugates were usually hydrolyzed more efficiently than their corresponding 6- and 7-analogs. Escherichia coli and jack bean enzymes were chosen to hydrolyse the glucosidic and N-acetylglucosaminidic conjugated bile acids, respectively.