STUDIES OF UDP-GLUCURONYLTRANSFERASE ACTIVITIES IN HUMAN-LIVER MICROSOMES

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Abstract
Human liver samples from a liver bank which were previously characterized by the ability to catalyze cytochrome P-450 dependent reactions were analyzed for various UDP-glucuronyltransferase activities. When stored at -80.degree. C, UDP-glucuronyltransferase activities and latency characteristics of the enzyme appeared to be stable for up to 2 yr. The correlation of UDP-glucuronyltransferase activity (4-methylumbelliferone as substrate) with enyzme activities towards 4-nitrophenol and 1-naphthol was much higher (r > 0.8) than that (r < 0.3) observed with other enzyme activities (4-hydroxybiphenyl, morphine and chloramphenicol as substrates), suggesting the presence of multiple enzyme forms in human liver. Livers of 3 patients treated with phenytoin or pentobarbital showed significantly higher UDP-glucuronyltransferase activities towards 1-naphthol, 4-methylumbelliferone and bilirubin than those from 5 patients who did not receive these inducing agents.