Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The glucuronidation of diflunisal to its phenolic (DPG) and acyl glucuronide (DAG) was measured in vitro using microsomes prepared from rat (n = 4) and human (n = 6) liver and kidney tissue. UGT activities towards bilirubin, 4-nitrophenol and (-)-morphine were also determined. 2. beta-Glucuronidase activity towards phenolphthalein glucuronide was much lower in microsomes prepared from human liver (45.2 +/- 3.1 Fishman Units/mg protein), human kidney (22.0 +/- 3.3 FU/mg), and rat kidney (25.1 +/- 2.5 FU/mg) as compared with rat liver (118.7 +/- 8.8 FU/mg). 3. The formation rate of DAG significantly increased when saccharo-1,4-lactone, a beta-glucuronidase inhibitor, was added to the rat liver microsomal incubation medium. beta-Glucuronidase inhibition, however, had little effect on the formation rate of DAG in human liver microsomes, and no effect in rat and human kidney microsomes. The formation of DPG was not affected by the microsomal beta-glucuronidase activity. 4. Unlike rat kidney microsomes, which only formed DAG, human kidney microsomes formed both diflunisal glucuronides. Formation of both diflunisal glucuronides in human kidney microsomes (Vmax = 0.97 +/- 0.21 and 0.27 +/- 0.07 nmol/min/mg for formation of DAG and DPG respectively) represented 60-70% of the activity found in liver microsomes (Vmax = 1.58 +/- 0.32 and 0.40 +/- 0.08 nmol/min/mg for formation of DAG and DPG respectively). 5. These results demonstrate that the in vitro glucuronidation rate of diflunisal may be affected by the microsomal beta-glucuronidase activity particularly when using rat liver microsomes. Our results also demonstrate that the human kidney has an important UGT-activity towards diflunisal.
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PMID:Glucuronidation of diflunisal in liver and kidney microsomes of rat and man. 886 97

Human uridinediphosphate-glucuronosyltransferase 1A1 (UGT1A1) was expressed in Salmonella typhimurium TA1535 cells by transfection of the cells with plasmids carrying the UGT1A1 cDNA. UGT1A1 cDNA was isolated by a polymerase chain reaction from human liver total RNA and was inserted into the pSE420 plasmid, linked to the trc promoter and terminator. The plasmid thus constructed was introduced into Salmonella TA1535 cells. The expression of human UGT1A1 protein was confirmed by Western blot analysis. The maximal expression was observed at 24 h after the addition of isopropyl-beta-D-thiogalactopyranoside, an inducer. However, the bilirubin conjugation activity of the membrane fraction from the Salmonella cells was not detectable. When a beta-glucuronidase inhibitor such as saccharic acid 1,4-lactone, glycyrrhizin or 1-naphtyl-beta-D-glucuronide was added to the reaction mixture, the bilirubin conjugation activity of the human UGT1A1 was detected. When geniposide was added to the reaction mixture, the bilirubin conjugation activity of UGT1A1 was not seen. Taking these results into account, the established Salmonella strain possesses the beta-glucuronidase activity. Since the beta-glucuronidase activity of the Salmonella was lower than that of E. coli, it was concluded that Salmonella seemed to be a good host to express UGT protein. This is the first study to demonstrate the establishment of a bacterial strain expressing native human UGT protein showing catalytic activity.
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PMID:Establishment of Salmonella strain expressing catalytically active human UDP-glucuronosyltransferase 1A1 (UGT1A1). 1082 Nov 20

The anti-HIV drug 3'-azido-3'-deoxythymidine (AZT) is the drug of choice for preventing maternal-fetal HIV transmission during pregnancy. Our aim was to assess the cytotoxic effects of AZT on human placenta in vitro. The mechanisms of AZT-induced effects were investigated using JEG-3 choriocarcinoma cells and primary explant cultures from term and first-trimester human placentas. Cytotoxicity measures included trypan blue exclusion, MTT, and reactive oxygen species (ROS) assays. Apoptosis was measured with an antibody specific to cleaved caspase-3 and by rescue of cells by the general caspase inhibitor Boc-D-FMK. The effect of AZT on the activities of glutathione-S-transferase, beta-glucuronidase, UDP-glucuronosyl transferase, cytochrome P450 (CYP) 1A, and CYP reductase (CYPR) in the placenta was assessed using biochemical assays and immunoblotting. AZT increased ROS levels, decreased cellular proliferation rates, was toxic to mitochondria, and initiated cell death by a caspase-dependent mechanism in the human placenta in vitro. In the absence of serum, the effects of AZT were amplified in all the models used. AZT also increased the amounts of activity of GST, beta-glucuronidase, and CYP1A, whereas UGT and CYPR were decreased. We conclude that AZT causes apoptosis in the placenta and alters metabolizing enzymes in human placental cells. These findings have implications for the safe administration of AZT in pregnancy with respect to the maintenance of integrity of the maternal-fetal barrier.
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PMID:3'-azido-3'-deoxythymidine (AZT) induces apoptosis and alters metabolic enzyme activity in human placenta. 1455 Jul 50

We have investigated the hypothesis that uridine 5'-diphosphate (UDP)-glucuronyltransferases (UGTs) and beta-glucuronidase are jointly involved in a mechanism for the storage and mobilization of iodothyronine metabolites in liver, kidney, heart and brain. Specifically, we predicted UGT activities to decrease and increase respectively, and beta-glucuronidase activity to increase and decrease respectively in hypo- and hyperthyroidism. To this end we have studied the effects of thyroid status on the activities of different enzymes involved in thyroid hormone metabolism in liver, kidney, heart and brain from adult rats with experimentally induced hypo- and hyperthyroidism. We used whole organ homogenates to determine the specific enzyme activities of phenol- and androsteron-UGT, beta-glucuronidase, as well as iodothyronine deiodinase types I and II. Deiodinase type I activities in liver and kidney were decreased in hypothyroid animals and, in liver only, increased in hyperthyroidism. Deiodinase type II activity was increased in hyperthyroid rat kidney only. Interestingly, in the heart, deiodinase type I-specific activity was increased fourfold, although the increase was not statistically significant. Cardiac deiodinase type I activity was detectable but not sensitive to thyroid status. Hepatic phenol-UGT as well as androsteron-UGT activities were decreased in hypothyroid rats, with specific androsteron-UGT activities two to three orders of magnitude lower than phenol-UGT activities. Both UGT isozymes were well above detection limits in heart, but appeared to be insensitive to thyroid status. In contrast, cardiac beta-glucuronidase activity decreased in hypothyroid tissue, whereas the activity of this enzyme in the other organs investigated did not change significantly. In summary, cardiac beta-glucuronidase, albeit in low levels, and hepatic phenol-UGT activities were responsive only to experimental hypothyroidism. Although a high basal activity of the pleiotropic beta-glucuronidase masking subtle activity changes in response to thyroid status cannot be ruled out, we conclude that hepatic, renal and cardiac UGT and beta-glucuronidase activities are not regulated reciprocally with thyroid status.
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PMID:Activities of UDP-glucuronyltransferase, beta-glucuronidase and deiodinase types I and II in hyper- and hypothyroid rats. 1517 87

Chloramphenicol (CP), a broad spectrum antibiotic, is eliminated in humans by glucuronidation. The primary UGT enzymes responsible for CP O-glucuronidation remain unidentified. We have previously identified the 3-O-CP (major) and 1-O-CP (minor) glucuronides by beta-glucuronidase hydrolysis, liquid chromatography-tandem mass spectrometry, and 1D/2D H NMR. Reaction phenotyping for the glucuronidation of CP with 12 expressed human liver UGT isoforms has identified UGT2B7 as having the highest activity for 3-O- and 1-O-CP glucuronidation with minor contributions from UGT1A6 and UGT1A9. The kinetics of CP 3-O-glucuronidation by pooled human liver microsomes (HLMs) exhibited biphasic Michaelis-Menten kinetics with the apparent high-affinity K(m1) and low-affinity K(m2) values of 46.0 and 1027 microM, whereas expressed UGT2B7 exhibited Michaelis-Menten kinetics with the apparent K(m) value of 109.1 microM. The formation of 1-O-CP glucuronide by pooled HLM and expressed UGT2B7 exhibited substrate inhibition kinetics with apparent K(m) values of 408.2 and 115.0 microM, respectively. Azidothymidine (AZT) and hyodeoxycholic acid (substrates of UGT2B7) inhibited 3-O- and 1-O-CP glucuronidation in pooled HLMs. In 10 donor HLM preparations, both CP 3-O- and CP 1-O-glucuronidation showed a significant correlation with AZT glucuronidation (UGT2B7) (r(s) = 0.85 and r(s) = 0.83, respectively) at 30 microM CP, whereas no significant correlation was observed between CP 3-O-glucuronidation and serotonin glucuronidation (UGT1A6) or propofol glucuronidation (UGT1A9) at this CP concentration. These results suggest that UGT2B7 is the primary human hepatic UDP-glucuronosyltransferase isoform catalyzing 3-O- and 1-O-CP glucuronidation with minor contributions from UGT1A6 and UGT1A9.
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PMID:Identification of human UGT2B7 as the major isoform involved in the O-glucuronidation of chloramphenicol. 2000 37