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The presence of a microsomal UDP‐glucuronyl transferase for bilirubin in homozygous jaundiced gunn rats and in the crigler‐najjar syndrome
Author(s) -
Odell Gerard B.,
Cukier Julio O.,
Gourley Glenn R.
Publication year - 1981
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.1840010405
Subject(s) - glucuronidation , microsome , bilirubin , chemistry , transferase , demethylation , glucuronosyltransferase , unconjugated hyperbilirubinemia , enzyme , in vitro , medicine , endocrinology , biochemistry , gene expression , dna methylation , gene
The infusion of a closely related derivative of bilirubin, its dimethyl diester (DME), into jaundiced ( jj ) Gunn rats was associated with biliary excretion of mono‐and diglucuronides of bilirubin. In vitro incubation of DME with liver microsomes from jj rats demonstrated sequential demethylation and glucuronidation of DME. Liver microsomes from a patient with the Crigler‐Najjar syndrome were unable to form glucuronides of bilirubin in vitro unless DME was used as substrate. The results suggest that the deficiency in Gunn rats and in the Crigler‐Najjar syndrome may be due to a structural defect in the microsomal matrix which contains glucuronyl transferase. This interpretation envisions a microenvironment of the transferase enzyme which is either impermeable to bilirubin or induces conformational changes which interfere with glucuronidation.