Enzymatic conversion of bilirubin monoglucuronide to diglucuronide by rat liver plasma membranes

P. L M Jansen, Jayanta Roy-Chowdhury, E. B. Fischberg, I. M. Arias

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

Formation of bilirubin monoglucuronide from unconjugated bilirubin requires a microsomal enzyme, UDP-glucunorate glucuronyltransferase (EC 2.4.1.17). Conversion of bilirubin monoglucuronide to bilirubin diglucuronide, the major bilirubin conjugate in bile, was studied in subcellular fractions of rat liver. The highest specific activity for bilirubin diglucuronide formation occurred in a fraction highly enriched in plasma membranes. Studies of reaction stoichiometry and utilization of UDP-D-[14C]glucuronic acid revealed that conversion of bilirubin monoglucuronide to bilirubin diglucuronide is not catalyzed by UDP-glucuronyl-transferase, and results from transglucuronidation of bilirubin diglucuronide and unconjugated bilirubin. When unconjugated bilirubin was infused intravenously into rats at rates exceeding the maximal hepatic excretory capacity, bilirubin monoglucuronide accumulated in serum and bilirubin diglucuronide was found exclusively in bile as the predominant bilirubin metabolite. These results suggest that formation of bilirubin diglucuronide occurs at the surface membrane of the liver cell. Conversion of bilirubin monoglucuronide to bilirubin diglucuronide may play a role in the transport of bilirubin glucuronides from liver to bile.

Original languageEnglish (US)
Pages (from-to)2710-2716
Number of pages7
JournalJournal of Biological Chemistry
Volume252
Issue number8
StatePublished - 1977

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Cell membranes
Liver
Rats
Cell Membrane
Bilirubin
Bile
Glucuronosyltransferase
Uridine Diphosphate
Glucuronic Acid
Subcellular Fractions
Metabolites
bilirubin diglucuronide
bilirubin glucuronate
Stoichiometry
Membranes
Enzymes
Serum

ASJC Scopus subject areas

  • Biochemistry

Cite this

Enzymatic conversion of bilirubin monoglucuronide to diglucuronide by rat liver plasma membranes. / Jansen, P. L M; Roy-Chowdhury, Jayanta; Fischberg, E. B.; Arias, I. M.

In: Journal of Biological Chemistry, Vol. 252, No. 8, 1977, p. 2710-2716.

Research output: Contribution to journalArticle

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