Formation of bilirubin glucoside.
1. Rat liver microsomal preparation can effect the transglucosylation from UDP-glucose to bilirubin in the presence of Mg(2+). 2. Other nucleotides, namely CDP-glucose, ADP-glucose and GDP-glucose, were not active as glucosyl donors. 3. Only trace amounts of galactose, galacturonic acid and N-acetylglucosamine were conjugated to bilirubin when their respective UDP derivatives were used in the reaction mixture. 4. The azobilirubin glucosides produced by coupling with p-diazobenzenesulphonic acid and diazotized ethyl anthranilic acid were separable from the corresponding azobilirubin glucuronides by t.l.c. 5. The glucoside was, however, hydrolysed by both beta-glucosidase and various preparations of beta-glucuronidase; azobilirubin and glucose were liberated in the process. 6. Kinetic studies showed that the effects of pH and Mg(2+) on the two conjugating systems were similar. 7. The specific activities of hepatic bilirubin UDP-glucosyltransferase, expressed as mug of bilirubin ;equivalents' conjugated/h per mg of protein, are respectively 1.7 and 2.4 for male and female rats. 8. The K(m) values for bilirubin and UDP-glucose are 5.7x10(-5)m and 1.6x10(-3)m respectively. 9. The glucoside and glucuronide conjugations of bilirubin are discussed in relation to the availability of the conjugating agents and aglycone in the liver.
D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D001391:Azo Compounds; D001663:Bilirubin / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D003597:Cytosine Nucleotides / Q000378:metabolism; D005959:Glucosidases; D005964:Glucosyltransferases / Q000378:metabolism; D005965:Glucuronates / Q000378:metabolism; D005966:Glucuronidase; D006027:Glycosides / Q000096:biosynthesis*; D066298:In Vitro Techniques; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008862:Microsomes, Liver / Q000378:metabolism; D051381:Rats; D014500:Uracil Nucleotides / Q000378:metabolism
D001391:Azo Compounds; D003597:Cytosine Nucleotides; D005965:Glucuronates; D006027:Glycosides; D014500:Uracil Nucleotides; D000244:Adenosine Diphosphate; D005964:Glucosyltransferases; D005959:Glucosidases; D005966:Glucuronidase; D008274:Magnesium; D001663:Bilirubin