Bilirubin, conjugated

Jaundice (yellow color of skin, whites of the eyes) may occur when blood levels of bilirubin exceed normal (icterus). Jaundice may be characterized by an increase in unconjugated (indirect) bilirubin, conjugated (direct) bilirubin, or both. Accumulation of bilirubin (usually unconjugiated) in the brain (kernicterus) may result in death. When conjugated bilirubin increases, it may be excreted, giving a deep yeUow-red color to the urine. Examples of conditions associated with increased bilirubin and jaundice include the following. 

Fig. 1. Structures of some bilirubin conjugates and nature of the azo derivatives obtained by treatment with diazotized ethyl anthranilate. From Fevery et al. (F5), by kind permission of the Editor of The BiochemicalJoumal.

Enzyme activities are expressed as nanomoles of bilirubin conjugated in 10 minutes per milligram of protein (Ap) or as nanomoles of bilirubin conjugated in 10 minutes per gram wet weight equivalent of liver (Al). 

As bilirubin can be converted in vitro into mono- and diconjugates of glucuronic acid (H4, R9, S6, SIO) and of xylose (F5), it is useful to distinguish the bilirubin conjugation rate (BCR) from the group trans-... 

Abbreviations bilirubin (B), conjugated bilirubin (BC), bilirubin monoconjugate (BMC), bilirubin diconjugate (BDC), bilirubin conjugation rate (BCR), group transfer rate (GTR). 

Most assays are based on the transformation of bilirubin conjugates into azo derivatives (Section 4.3). In evaluating such methods, chromatographic analysis of the azo derivatives is a useful supplement to the study of color yields. A review on the diazo-coupling of bile pigments in various biological media, and on the separation and structure elucidation of the... 

As yet only a limited number of bilirubin conjugates can be synthesized in vitro. Mono- and diglucuronosides of bilirubin predominate in rat bile (F6, Hll, 03, S6). In accordance with these observations, isolated liver preparations and liver slices from rat (S6), and rat hepatoma cells (R9)... 

Al. Adlard, B. P. F., and Lathe, G. H., Breast milk jaundice effect of 3a,20 -preg-nanediol on bilirubin conjugation by human liver. Arch. Dis. Childhood 45,186-189... 

B2. Bakken, A. F., Bilirubin excretion in newborn human infants. I. Unconjugated bilirubin as a possible trigger for bilirubin conjugation. Acta Paediat. Scand. 59, 148-152 (1970). 

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