Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.5.1.18 (glutathione S-transferase)
 22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Metabolism of testosterone to various products (catalyzed by several different CYP isozymes) and the activities of phenol sulfotransferase (pST) and glutathione transferase (GST) in S9 fractions prepared from the mucosa of the duodenum, jejunum, ileum, caecum and upper and lower colon of male Sprague-Dawley rats were determined and compared to the corresponding hepatic and renal activities. Incubation of the S9 fraction prepared from the jejunum with testosterone and NADPH resulted in the formation of 2alpha-, 6alpha-, 6beta- and 16alpha-hydroxytestosterone and androstenedione at rates that were 1.6, 24, 1.3, 0.6 and 1.3%, respectively, of the corresponding hepatic values. The production of 2alpha-hydroxytestosterone was catalyzed only by the preparations from the duodenum and jejunum; whereas 6alpha-, 6beta- and 16alpha-hydroxytestosterone and androstenedione were produced in all regions of the intestine. In the case of the rat kidney, the rates of formation of the different testosterone metabolites were between 0.6 and 35% of the corresponding liver activity. The activity of glutathione transferase was approximately 12-26% of the corresponding hepatic activity throughout the intestine. The highest activity of phenol sulfotransferase was observed in the lower colon (almost 6% of the liver activity) and the lowest activity in the duodenum (1%). The renal activities of GST and pST were 70 and 1%, respectively, of the corresponding liver values. In summary, the metabolism of testosterone and the activities of GST and pST in rat intestine are generally low to very low in comparison to the corresponding activities in rat liver. In most cases, these activities are present throughout the entire intestine and not restricted to a particular portion(s) of this organ.
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PMID:Characterization of the rates of testosterone metabolism to various products and of glutathione transferase and sulfotransferase activities in rat intestine and comparison to the corresponding hepatic and renal drug-metabolizing enzymes. 1522 56

Activities of Phase II antioxidant enzymes, including NAD(P)H:quinone oxidoreductase 1 (NQO1), glutathione S-transferase (GST), UDP-glucuronosyltransferase (UGT), and phenol sulfotransferase 1A1 (SULT1A1) were measured in brain of August-Copenhagen Irish (ACI) rats exposed chronically to low doses of estradiol (E(2)). ACI rats were selected for study because this strain is highly responsive to treatment with low doses of E(2) as indexed by a high incidence of E(2)-induced mammary tumors compared to other strains. Rats were exposed chronically to 3 mg E(2) contained in cholesterol pellets implanted subcutaneously for 6 weeks. This treatment increased activities of all four enzymes in the striatum of male but not female ACI rats. Blood E(2) levels at time of sacrifice correlated closely with activities of striatal NQO1, GST, and SULT1A1, but not with striatal UGT. NQO1, GST, and SULT1A1 activities in other brain regions including the cortex, cerebellum, and hippocampus were less sensitive to chronic E(2) treatment. NQO1 was primarily localized in vascular elements and neurons and SULT1A1 primarily in neurons and neuropil of control and E(2)-treated rats. Collectively, these results suggest that enhanced expression of NQO1, GST, and SULT1A1 may contribute to the antioxidant effects of E(2) in the striatum, an area of the brain that may be particularly prone to oxidative stress because of its high content of catecholamines.
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PMID:Phase II antioxidant enzyme activities in brain of male and female ACI rats treated chronically with estradiol. 1682 82

Liver parenchymal cells (hepatocytes) of human organ donors were isolated using a two-step collagenase perfusion technique. The average viability of the freshly isolated liver parenchymal cells, as judged by trypan blue exclusion, was 82% (SD = 7%; n = 6). The inter-individual differences in the determined enzyme activities were less than a factor of 7.5, despite the different sexes and ages of the donors. Freshly isolated parenchymal cells (PC) were cryopreserved using a computer-controlled freezing protocol. After thawing, cryopreserved cells had a mean viability of 57% (SD = 18%; n = 6). The activities of xenobiotic metabolizing enzymes in freshly isolated and cryopreserved cells were compared using PC from two donors. The enzyme activities of phenol sulfotransferase, 1-naphthol UDP-glucuronosyltransferase and microsomal epoxide hydrolase were well maintained after thawing (87-117% of activities in freshly isolated cells), whereas the activities of glutathione S-transferase, monitored with the broad spectrum substrate 1-chloro-2,4-dinitrobenzene, and the major broad spectrum cytosolic epoxide hydrolase were moderately but markedly reduced after cryopreservation (34-64% and 45-89% of levels in fresh cells, respectively). The decrease of both activities was dependent on the viability after thawing. When cryopreserved cells were purified by a Percoll centrifugation after thawing, the viability was increased from 62 to 92% for cells from one of the donors and from 88 to 98% for PC for the other donor. Subsequently the activity of glutathione S-transferase in Percoll-purified PC from the two donors was increased to 71 and 96% of levels in freshly isolated cells. It is concluded that the use of cryopreserved liver parenchymal cells of humans and other species represents a valuable tool in predicting which animal species best represents humans in hepatic metabolism and therefore should be the preferred species for investigations of metabolism and metabolism-dependent toxicities.
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PMID:Xenobiotic metabolizing enzyme activities in isolated and cryopreserved human liver parenchymal cells. 2069 84

We developed a fluorescent assay to conveniently determine the kinetics of protein sulfation, which is essential for understanding interface between protein sulfation and protein-protein interactions. Tyrosylprotein sulfotransferase (TPST) catalyzes protein sulfation using 3'-phosphate 5'-phosphosulfate (PAPS) as sulfuryl group donor. In this report, PAPS was regenerated following sulfuryl group transfer between adenosine 3',5'-diphosphate and 4-methylumbelliferyl sulfate catalyzed by phenol sulfotransferase (PST). The TPST and PST coupled enzyme platform continuously generated fluorescent 4-methylumbelliferone (MU) that was used to real-time monitor protein sulfation. Using a recombinant N utilization substance protein A fused Drosophila melanogaster tyrosylprotein sulfotransferase, we demonstrated that the activity of TPST determined through MU fluorescence directly correlated with protein sulfation. Kinetic constants obtained with small P-selectin glycoprotein ligand-1 peptide (PSGL-1 peptide, MW 1541) or its large glutathione S-transferase fusion protein (GST-PSGL-1, MW 27833) exhibited significant variation. This assay can be further developed to a high-throughput method for the characterization of TPSTs and for the identification and screening of their protein substrates.
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PMID:Fluorescence assay for protein post-translational tyrosine sulfation. 2316 Oct 68


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