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)

We have demonstrated that a filamentous fungus Phanerochaete chrysosporium converts glyceryl trinitrate (GTN) into its di- and mononitrate derivatives concurrently with the formation of nitric oxide detected by electron paramagnetic resonance (EPR), and the formation of nitrite. The metabolisms of nitrite and nitrate by the fungus are evaluated and taken into account when considering GTN degradation. Lack of evidence for nitrate formation from GTN suggests that an esterase-type activity is not involved. Furthermore, the kinetics of appearance of the hemoprotein-NO and non-heme protein-NO (FeS-NO) complexes indicate that an enzymatic process producing NO directly from GTN may be involved concurrently with a glutathione transferase-like system.
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PMID:Nitroglycerin metabolism by Phanerochaete chrysosporium: evidence for nitric oxide and nitrite formation. 164 2

The incidence and phenotype of preneoplastic and neoplastic liver lesions appearing in LEC rats after recovery from severe hereditary hepatitis were studied in comparison with the liver lesions appearing in chemical liver carcinogenesis. The livers of 168 rats (90 male, 78 female) were stained for seven histochemical markers at different time periods from the 20th week to the 122nd week of life. Glucose-6-phosphatase (G6Pase), adenosine triphosphatase (ATPase) and non-specific esterase (ES) were used as negative markers. Gamma-glutamyltransferase (GGT), glutathione S-transferase placental form (GSTP), esterase isozyme L-1 (L1) and alpha-fetoprotein (AFP) were used as positive markers. The study on the incidence of liver lesions in the LEC rats revealed sequential development of liver foci, nodules and hepatocellular carcinomas (HCCs) similar to those seen in chemically induced liver carcinogenesis. These lesions appeared earlier and more frequently in male LEC rats than in female ones, suggesting the importance of hormonal environment in spontaneous HCC development. The histochemical analysis of spontaneous liver lesions in LEC rats showed that GSTP was the most reliable positive marker as previously reported in chemical liver carcinogenesis. There was no essential difference in the expression of the markers in spontaneous and chemically induced liver lesions except for L1, which is considered to be related to xenobiotic metabolism. The results of this study suggest that both spontaneous and chemically induced liver cancer may develop by passing through phenotypically similar preneoplastic processes. In addition, the LEC rat uniquely showed chronic liver damage (hepatocyte death and regeneration) at the promotion stage of carcinogenesis. Such a natural history of HCC development in LEC rats is similar to that of human HCC which is frequently associated with chronic liver damage. Thus, the LEC rat provides a useful model for studying the process and underlying mechanisms of human liver cancer development.
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PMID:Phenotype of preneoplastic and neoplastic liver lesions during spontaneous liver carcinogenesis of LEC rats. 169 69

Several enzymes of amino acid and carbohydrate metabolism were studied in primary cultures of fetal rat hepatocytes. One day after plating, activity of both esterase and gamma-glutamyl transpeptidase decreased to half of the freshly isolated hepatocytes, and then remained constant. Acid phosphatase revealed lower activity after plating but recovered to the same levels of isolated cells on day-8. Leucine aminopeptidase and glutathione S-transferase showed a peak of activity respectively on day-6 and day-8. On the other hand, activities of glucose-6-phosphate dehydrogenase, hexokinase and pyruvate kinase increased linearly from Day-1, but only pyruvate kinase reached a plateau on Day-2. These results suggest that different patterns of enzyme activities in the culture might be a reflection, both of a release from homeostatis and adaptation to a new environment.
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PMID:[Enzyme activities in cultured fetal rat hepatocytes]. 286 56

The activity of three enzymatic systems of xenobiotic metabolism (cytochrome P-450-dependent monooxygenases, non-specific esterases and glutathione S-transferases) was studied in sensitive (S) and resistant to tetrametrin (Rtetr.), permetrin (Rperm.), mecarbenyl (Rmec.) and chlorophos (Rchlor.) strains of the housefly M. domestica L. In Rtetr. and Rmec., the activity of microsomal monooxygenases was increased 2.7- and 2.3-fold, respectively, as compared to S. The position of maxima of CO-difference spectra of cytochrome P-450 in all resistant strains (with the exception of Rchlor.) were shifted towards the short-wave region by 1-2 nm. The activity of glutathione S-transferase in Rtetr. was increased as compared to S. Analysis of the total esterase activity and electrophoresis in starch gel revealed quantitative and qualitative differences between the strains under study. In all resistant strains, except for Rmec., additional bands corresponding to the esterase activity were observed. The experimental results are discussed in terms of resistance of insects to insecticides.
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PMID:[The role of enzymes of xenobiotic metabolism in the resistance of insects to insecticides]. 369 17

The authors studied the effect of a long-term intragastric administration to CBA X C57Bl/6 male mice of T-2 toxin in doses of 0.067 mg/kg bw a day (1/100 of the LD50) or 0.33 and 0.45 mg/kg a day (1/20 and 1/15 of the LD50) on the liver content of protein, cytochrome P-450 SH-glutathione and on the activity of 10 lysosomal and microsomal enzymes and glutathione transferase. A dose-dependent increase in the activity of lysosomal hydrolases and glutathione transferase localized in cytosol was revealed together with a fall in the activity of microsomal aniline hydroxylase, carboxyl esterase and epoxide hydrolase. Emphasis is laid on a dose-dependent reduction in the liver of nonsedimented activity of lysosomal enzymes. In T-2 mycotoxicosis, the most sensitive and the most stable parameter was the activity of lysosomal enzymes in blood serum. That activity also declined during the recovery period, namely 3 months after discontinuance of toxin administration. Both groups of mice showed a progressive decrease in the blood leukocyte count and lysozyme content, whereas in the spleen, there was a decrease in the number of antibody-forming cells. It is concluded that biochemical, hematological and hematological characteristics should be taken into consideration in evaluating the chronic action of T-2 toxin.
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PMID:[Biochemical, hematological and immunological criteria for assessing chronic T-2 mycotoxicosis in mice]. 406 Jun 87

Young male C57BL mice were exposed nose-only to cigarette smoke 20 min/day for 8 weeks while maintained on diets containing 0, 5, and 100 ppm of vitamin E. Smoking had no effect on hepatic aryl hydrocarbon hydroxylase (AHH), UDP-glucuronyltransferase, glutathione S-transferase, parathion desulfurase, or parathion esterase activity. Lung AHH activity was increased in all smoke-exposed mice, although the increase was significantly less in animals maintained on the vitamin E-free diet. All mice on the vitamin E-free diet showed reduced lung AHH activity and increased hepatic lipid peroxidation. No other biotransformations tested were significantly altered by varying vitamin E concentrations alone or in combination with cigarette smoke. For all vitamin E diets, both the smoke-exposed and sham-treated mice gained significantly less weight than the control animals. This effect was attributed to stress induced by restraint of the animals within the smoking apparatus. The results of these experiments show that both cigarette smoke and vitamin E-deficient diets may affect xenobiotic metabolism but that the combination does not appear to alter markedly their individual effects or to induce ones not previously observed.
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PMID:Effects of cigarette smoke and dietary vitamin E levels on selected lung and hepatic biotransformation enzymes in mice. 406 31

The principal biochemical mechanisms of resistance to insecticides involve either modified, less sensitive cholinesterase, esterase action, glutathione S-transferase action or cytochrome P-450-dependent monooxygenation. Both quantitative and qualitative differences in cytochrome P-450 isozymes are under genetic control and both are related to resistance. Recent characterization studies involving ligand binding and multiplicity of isozymes in Musca domestica (the housefly) are discussed in relation to resistance. The recent demonstration that multiple isozymes of glutathione S-transferase exist in susceptible and resistant insects is of interest, and some re-examination of their role in the mechanism of resistance is required. Esterases are a heterogeneous group of enzymes whose role in resistance has often been suggested but seldom rigorously defined. Purification studies in the green rice leafhopper, Nephotettix cincticeps, have involved an enzyme with carboxylesterase, phosphotriesterase and pyrethroid esterase activities. A similar enzyme, but without pyrethroid esterase activity, is also found in the housefly. In resistance such enzymes may serve either to catalyse hydrolysis or as binding proteins. It has been suggested, from time to time, that regulator genes, enzyme induction and gene magnification all play a part in controlling biochemical mechanisms of resistance, although clearly defined evidence has not always been brought forward. These hypotheses are re-examined.
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PMID:Biochemical mechanisms of resistance to insecticides. 655 14

(1) The genetics of malathion resistance in two strains of the flour beetle, Tribolium castaneum, was investigated. In CTC-12, resistance is polygenic, while in Kano, it is due to a dominant allele at a single autosomal locus. Reciprocal hybrids with the susceptible control strains bb and pp showed an overdominant response in particular when Kano was the male parent in the original cross. (2) Three possible genetic mechanisms to explain these results are discussed. The model which best explains the genetic results, particularly the difference between the reciprocal crosses, assumes a modifier resistance allele on the Y chromosome. (3) The levels of activity of total esterases, carboxylesterases, mixed-function oxidases, epoxide hydrase, and glutathione transferase in the parent strains and their hybrids were measured quantitatively. Although total esterase activity may not be relevant for the breakdown of malathion, it was inhibited by the pesticide. The activity of the microsomal enzymes was high in CTC-12, low in bb, and intermediate in the hybrids, while carboxylesterases were very active in Kano as well as in the hybrids with bb and low in the latter. These patterns agree with the genetics of resistance in the two strains. A higher level of GSH transferase in the Kano x bb hybrids than in Kano seems to indicate a possible biochemical mechanism for their overdominant resistance.
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PMID:Malathion resistance in Tribolium strains and their hybrids: inheritance patterns and possible enzymatic mechanisms (Coleoptera, Tenebrionidae). 713 93

The resistance status of 14 strains of Blattella germanica (L.) from four countries was determined for chlorpyrifos and propoxur compared with a standard reference susceptible strain. Thirteen strains were resistant to chlorpyrifos; 12 strains were resistant to propoxur. Resistance ratios for chlorpyrifos ranged from 8- to 462-fold at LC90; for propoxur, resistance ratios ranged from 4- to 46-fold. One cockroach strain from Denmark had negative cross-resistance to chlorpyrifos, and one strain from the United States had negative cross-resistance to propoxur. Slopes of probit regressions indicated that all resistant strains were heterogeneous for resistance to both chlorpyrifos and propoxur. Synergist studies with piperonyl butoxide indicated that multifunction mono-oxidases are probably involved in resistance to chlorpyrifos in six strains and in resistance to propoxur in seven strains. Esterase activity was elevated in 10 strains; of these strains, two had only slightly elevated esterase activity as measured with the substrates 1- and 2-naphthyl acetate. The remainder had higher levels of elevated esterase activity to both substrates. Strains with elevated esterase activity were resistant to a broad spectrum of organophosphates, pyrethroids, or both. Increased levels of glutathione S-transferase activity were found in four strains. Another two strains had a low frequency (1%) of individuals with high glutathione S-transferase activity. Elevated glutathione S-transferase activity was not correlated with the observed levels of organophosphate or carbamate resistance. One strain from Dubai had an altered acetylcholinesterase-based mechanism that conferred broad-spectrum resistance to a range of organophosphates and carbamates.
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PMID:Possible mechanisms of organophosphorus and carbamate insecticide resistance in German cockroaches (Dictyoptera: Blattelidae) from different geographical areas. 750 2

Rat liver and house fly, Musca domestica L., glutathione S-transferases were purified by affinity chromatography and chromatofocusing. The specific activity with alpha-naphthyl acetate (a substrate, for general esterase activity) was determined. Some of the esterase activity that is normally assayed for resistance is apparently caused by the activity of the glutathione S-transferase.
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PMID:Glutathione S-transferases: alpha-naphthyl acetate activity and possible role in insecticide resistance. 765 98


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