Glucuronidation of thyroxine is a major metabolic pathway facilitating its excretion. In this study, we characterized the glucuronidation of thyroxine in human liver, jejunum, and kidney microsomes, and identified human UDP-glucuronosyltransferase (UGT) isoforms involved in the activity. Human jejunum microsomes showed a lower K(m) value (24.2 microM) than human liver (85.9 microM) and kidney (...

Polychlorinated biphenyls (PCBs) can be metabolized by cytochromes P450 to hydroxylated biotransformation products. In mammalian studies, some of the hydroxylated products have been shown to be strong inhibitors of steroid sulfotransferases. As a part of ongoing research into the bioavailability of environmental pollutants in catfish intestine, we investigated the effects of a series of hydroxy...

We characterized the hepatic and intestinal UDP-glucuronosyltransferase (UGT) isoform(s) responsible for the glucuronidation of 2-(4-chlorophenyl)-5-(2-furyl)-4-oxazoleacetic acid (TA-1801A) in humans through several in vitro mechanistic studies. Assessment of a panel of recombinant UGT isoforms revealed the TA-1801A glucuronosyltransferase activity of UGT1A1, UGT1A3, UGT1A7, UGT1A9, and UGT2B7...

The microsomal enzyme uridine diphosphate (UDP) glucuronate glucuronyltransferase (E.C. 2.4.1.17) catalyzes formation of bilirubin mono-glucuronide from bilirubin and UDPglucuronic acid. Bilirubin glucuronoside glucuronosyltransferase (E.C. 2.4.1.95), an enzyme concentrated in plasma membrane-enriched fractions of rat liver, converts bilirubin monoglucuronide to bilirubin diglucuronide. Bilirub...

Denopamine is one of the oral beta(1)-adrenoceptor-selective partial agonists. Denopamine glucuronide is the most abundant metabolite in human, rat, and dog urine when administered orally. Species differences in denopamine glucuronidation were investigated with liver microsomes obtained from humans and experimental animals. In rat and rabbit, only the phenolic glucuronide was detected, whereas ...