title: Mechanism of biosynthesis of thio- -D-glucuronides and thio- -D-glucosides.
abstract: 1. The thio-beta-d-glucosiduronic acids (thio-beta-glucuronides) of o-aminothiophenol, diethyldithiocarbamic acid, p-nitrothiophenol and thiophenol are formed biosynthetically in broken- and intact-cell preparations of mouse liver. 2. For this biosynthesis to occur in homogenates or microsomal fractions, UDP-glucuronic acid was required during incubation; glucose, glucuronic acid or UDP could not replace it. UDP was a product of the reaction. 3. The biosynthetic mechanism linking glucuronic acid to thiol and carbodithioic groups therefore requires UDP-glucuronyltransferase activity and resembles that forming the various types of O-glucuronides. 4. An analogous enzymic mechanism employing UDP-glucose synthesizes the thio-beta-d-glucosides of diethyldithiocarbamic acid and thiophenol in gut preparations of the mollusc Arion ater; this mechanism resembles that forming the O-glucosides. The thio-beta-d-glucosides are formed also in intact cells. 5. As expected from the distribution of O-glycosides, S-glucuronides of these aglycones were not detectable with the invertebrate, nor were the S-glucosides with the vertebrate. 6. Despite their similar biosyntheses, S- and O-beta-glycosides differ in susceptibility to hydrolysis by beta-glycosidases. Rat preputial-gland beta-glucuronidase hydrolysed thioglucuronides of o-aminothiophenol, diethyldithiocarbamic acid and p-nitrothiophenol, hydrolysis being inhibited by glucarolactone; the thioglucuronide of thiophenol was not hydrolysed by preputial-gland or liver beta-glucuronidase. The two S-glucosides resisted hydrolysis by beta-glucosidase from almond emulsin.
mesh_terms: D000818:Animals; D005959:Glucosidases; D005965:Glucuronates / Q000096:biosynthesis*; D005966:Glucuronidase; D006027:Glycosides / Q000096:biosynthesis*; D006602:Hexosyltransferases / Q000378:metabolism; D006868:Hydrolysis; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D051379:Mice; D008862:Microsomes, Liver / Q000378:metabolism; D008974:Mollusca; D009596:Nitrophenols / Q000378:metabolism; D010636:Phenols / Q000378:metabolism; D051381:Rats; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013440:Sulfides / Q000096:biosynthesis*; D013859:Thiocarbamates / Q000378:metabolism
chemical_list: D005965:Glucuronates; D006027:Glycosides; D009596:Nitrophenols; D010636:Phenols; D013438:Sulfhydryl Compounds; D013440:Sulfides; D013859:Thiocarbamates; D006602:Hexosyltransferases; D005959:Glucosidases; D005966:Glucuronidase