Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

A full length cDNA clone, pGTB38 (C. B. Pickett et al. (1984) J. Biol. Chem. 259, 5182-5188), complementary to a rat liver glutathione S-transferase Ya mRNA has been expressed in Escherichia coli. The cDNA insert was isolated from pGTB38 using MaeI endonuclease digestion and was inserted into the expression vector pKK2.7 under the control of the tac promoter. Upon transformation of the expression vector into E. coli, two protein bands with molecular weights lower than the full-length Ya subunit were detected by Western blot analysis in the cell lysate of E. coli. These lower-molecular-weight proteins most likely result from incorrect initiation of translation at internal AUG codons instead of the first AUG codon of the mRNA. In order to eliminate the problem of incorrect initiation, the glutathione S-transferase Ya cDNA was isolated from the expression vector and digested with Bal31 to remove extra nucleotides from the 5' noncoding region. The protein expressed by this expression plasmid, pKK-GTB34, comigrated with the Ya subunit on sodium dodecyl sulfate polyacrylamide gels and was recognized by antibodies against the YaYc heterodimer. The expressed Ya homodimer was purified by S-hexylglutathione affinity and ion-exchange chromatographies. Approximately 50 mg pure protein was obtained from 9 liters of E. coli culture. The expressed Ya homodimer displayed glutathione-conjugating, peroxidase, and isomerase activities, which are identical to those of the native enzyme purified from rat liver cytosol. Protein sequencing indicates that the expressed protein has a serine as the NH2 terminus whereas the NH2 terminus of the glutathione S-transferase Ya homodimer purified from rat liver cytosol is apparently blocked.
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PMID:Expression of a cDNA encoding a rat liver glutathione S-transferase Ya subunit in Escherichia coli. 264 28

Tumor tissue and nontumorous tissue of 31 patients with testicular tumor were examined by the peroxidase antiperoxidase (PAP) procedure using the primary antibody against glutathione S-transferase (GST). Histology of primary tumor was classified as seminoma in 10 cases, non-seminoma in 18 (including 2 cases of yolk sac tumor), and malignant lymphoma in 3. Tumorous tissues except one with yolk sac tumor failed to be stained with GST. The seminiferous tubules of the nontumorous testicular tissue had a positive reaction in the infant cases, but not in the adult cases. The degenerated seminiferous tubules involved in the testicular tumors also had a positive reaction in all the cases. Leydig cells had a positive reaction in all the cases. In particular, diffuse Leydig cell's hyperplasia was observed in a case with high serum beta hCG and urinary hCG levels. These data may be relevant in explaining the inherent hypofertility of these patients.
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PMID:[Histochemical study on glutathione S-transferase in patients with testicular tumor]. 265 72

Glutathione S-transferases are a group of drug metabolising and detoxification enzymes. We have studied the distribution of four isoenzymes, acidic, basic, neutral, and microsomal GST in human liver, gall bladder, and small and large intestinal epithelium by immunohistochemistry. Antibodies were raised in rabbits to purified GST subunits and several formalin fixed paraffin sections of each human tissue studied using the peroxidase-antiperoxidase method. Staining density was graded from very strong (+++) to negative (-). All four enzymes were identified within the liver, the acidic GST being found almost exclusively within the biliary epithelium. The gall bladder epithelium stained strongly for acidic and basic GST. In the small intestinal epithelium the acidic and neutral GST were readily identified in villi and crypts, whilst basic GST was found only in the villi and microsomal only in the crypts. In the colonic mucosa only acidic GST could consistently be identified. This histological heterogeneity may have functional implications for these enzymes in human hepatobiliary and intestinal tissue.
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PMID:Cytosolic and microsomal glutathione S-transferase isoenzymes in normal human liver and intestinal epithelium. 275 9

Inhibition of the enzyme activity of glutathione S-transferase (GST) by a physiological concentration of bilirubin was studied using various substrates. When rat liver cytosol was used as an unfractionated GST, its GSH-conjugation activity toward 1-chloro-2,4-dinitrobenzene was decreased to one-half by bilirubin, while the activity toward 1,2-dichloro-4-nitrobenzene, p-nitrobenzyl chloride, or 1,2-epoxy-(p-nitrophenoxy)propane and also the non-selenium dependent GSH-peroxidase activity toward cumene hydroperoxide (CHPx activity) were hardly affected under the same conditions. In contrast, bilirubin inhibited each of the purified GST isozymes and no remarkable difference in bilirubin inhibition was observed with any of the substrates tested. From the chromatographic analysis of the cytosol incubated with [3H]bilirubin, it was found that a major part of the added bilirubin binds to subunit 1 (Ya) of GST isozyme, leaving not only the conjugation activity derived from 3-4 type GST but also the CHPx activity of subunit 2 (Yc) quantitatively intact. The bilirubin inhibition of both the conjugation activity of GST 3-4 and the CHPx activity of GST 2-2 was prevented almost completely by addition of a 3-fold molar excess of GST 1-1. From these results, it was assumed that the enzyme activities of both 3-4 type GSTs and subunit 2 (Yc) were protected from the inhibitory action of bilirubin by the scavenger effect of subunit 1 (Ya).
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PMID:Protection of glutathione S-transferase from bilirubin inhibition. 276 23

Human placental form of glutathione S-transferase (GST-pi) was detected in 38 human gastric carcinoma and 28 precancerous lesions by Avidin biotin peroxidase complex (ABC) method using anti-GST-pi antibody. Of 22 normal gastric mucosa, 91% were negative for GST-pi stain, 95% of 21 well and moderately differentiated gastric adenocarcinomas, all of 5 poorly differentiated gastric adenocarcinomas, 75% of undifferentiated gastric carcinomas, 85% of intestinal metaplasia and 100% of atypical hyperplasia were positive for GST-pi stain. These results indicate that GST-pi is a new sensitive marker for immunohistochemical detection of gastric carcinoma and precancerous lesion.
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PMID:[Value of immunohistochemical investigation of anti-GST-pi antibody in the early diagnosis of gastric carcinoma and precancerous lesion]. 280 39

The 15,000xg supernatant of sonicated rat PMN contains 5-lipoxygenase that converts arachidonic acid to 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and leukotriene A4 and an HPETE peroxidase that catalyzes reduction of the 5-HPETE. The specificity of this HPETE peroxidase for peroxides, reducing agents, and inhibitors has been characterized to distinguish this enzyme from other peroxidase activities. In addition to 5-HPETE, the HPETE peroxidase will catalyze reduction of 15-hydroperoxyeicosatetraenoic acid, 13-hydroperoxyoctadecadienoic acid, and 15-hydroperoxy-8,11,13-eicosatrienoic acid, but not cumene or t-butylhydroperoxides. The HPETE peroxidase accepted 5 of 11 thiols tested as reducing agents. However, glutathione is greater than 15 times more effective than any other thiol tested. Other reducing agents, ascorbate, NADH, NADPH, phenol, p-cresol, and homovanillic acid, were not accepted by HPETE peroxidase. This enzyme is not inhibited by 10 mM KCN, 2 mM aspirin, 2 mM salicylic acid, or 0.5 mM indomethacin. When 5-[14C]HPETE is generated from [14C]arachidonic acid in the presence of unlabeled 5-HPETE and the HPETE peroxidase, the 5-[14C]HETE produced is of much lower specific activity than the [14C]arachidonic acid. This indicates that the 5-[14C]HPETE leaves the active site of 5-lipoxygenase and mixes with the unlabeled 5-HPETE in solution prior to reduction and is a kinetic demonstration that 5-lipoxygenase has no peroxidase activity. Specificity for peroxides, reducing agents, and inhibitors differentiates HPETE peroxidase from glutathione peroxidase, phospholipid-hydroperoxide glutathione peroxidase, a 12-HPETE peroxidase, and heme peroxidases. The HPETE peroxidase could be a glutathione S-transferase selective for fatty acid hydroperoxides.
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PMID:Specificity of an HPETE peroxidase from rat PMN. 285 18

Photoemissive excited species are produced by the horseradish peroxidase (HRP)-catalyzed oxidation of reduced glutathione (GSH), without exogenously added hydroperoxide under aerobic conditions. The emitted low-level chemiluminescence consisted of two phases. Light emission occurred at wavelengths beyond 610 nm (greater than or equal to 90% intensity), indicative of singlet oxygen 1O2. Deuterium oxide enhanced photoemission 4.4-fold. Ascorbate inhibited chemiluminescence completely. In the absence of GSH or when GSH was replaced by the disulfide, no red chemiluminescence was observed. The glutathionyl radical GS. is most likely to be involved in both phases of light emission. Further, the superoxide radical plays a role, as substantiated by the inhibitory effect of superoxide dismutase. Both phases of photoemission were abolished by glutathione peroxidase; thus hydroperoxides are regarded as essential intermediates for the formation of excited species. Catalase abolished phase I and did not affect phase II. In contrast, glutathione S-transferase 1-2 (showing peroxidase activity towards organic hydroperoxides but not towards H2O2) inhibited phase II, whereas phase I was still present. Glutathione sulfonate and the disulfide GSSG were detected as oxidation products from GSH under conditions where phase II chemiluminescence was observed. HRP Compound III accumulated during the reaction. It is concluded that phase I is dependent on exogenously added or endogenously generated H2O2, whereas phase II does not require H2O2 but an organic peroxy species. A mechanism based on chain reactions involving oxygen addition to the thiyl radical is proposed. Sulfenyl peroxy species are suggested as transient intermediates in reactions finally leading to the generation of excited states such as singlet molecular oxygen.
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PMID:Excited species generation in horseradish peroxidase-mediated oxidation of glutathione. 301 81

In two Adriamycin (Adr) resistant sublines (GLC4-Adr1 and GLC4-Adr2) of a human small cell lung carcinoma cell line, GLC4, cross-resistance for radiation was found. GLC4-Adr1 has an acquired Adr resistance factor of 44 after culturing without Adr for 20 days and GLC4-Adr2, the same subline cultured without Adr for 3 months, has a decreased but stable resistance factor of 8. One of the assumed mechanisms of Adr is that the effect is mediated through the formation of free radicals. Therefore free radical scavenging might play a role in these Adr resistant cell lines. Adr, H2O2, and X-ray induced cytotoxicity were evaluated. Glutathione (GSH) levels and activities of associated enzymes were determined as well as Adr, H2O2, and X-ray induced DNA breaks and repair. GSH level was decreased in GLC4-Adr1, but restored to the normal level in GLC4-Adr2. Superoxide dismutase, catalase, glutathione-peroxidase, and glutathione S-transferase were not elevated in the resistant sublines. Adr induced a decreased amount of DNA breaks in GLC4-Adr1 compared to GLC4. For X-ray and H2O2 a comparable amount of DNA damage was found. GLC4-Adr1 was able to repair DNA breaks induced by Adr, X-ray, and H2O2 better than GLC4. In conclusion, no increased enzyme capacity for detoxification of free radicals could be detected in the cytosol of the resistant cells. The resistance against free radicals in the GLC4-Adr1 line may at least in part be a result of increased DNA repair.
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PMID:Role of free radicals in an adriamycin-resistant human small cell lung cancer cell line. 304 Feb 27

Human placental form of glutathione S-transferase (GST-pi) was detected in human colonic carcinomas and adenomas by peroxidase anti-peroxidase method using antibody raised against GST-pi. Of 60 carcinomas, including differentiated adenocarcinomas and undifferentiated carcinomas, 88% were positive for GST-pi staining, and 47% of 23 adenomas were also positive. In the normal colonic mucosa, GST-pi was not detectable or was only weakly stained in the basal parts of the absorptive cells or in the cytoplasm of the cells containing little mucin. These results indicate that GST-pi is a possible new marker for immunohistochemical detection of human colonic carcinoma and some adenomas.
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PMID:Human placental form of glutathione S-transferase (GST-pi) as a new immunohistochemical marker for human colonic carcinoma. 308 12

Glutathione S-transferase was isolated from supernatant of camel kidney homogenate centrifugation at 37,000 xg by glutathione agarose affinity chromatography. The enzyme preparation has a specific activity of 44 mumol/min/mg protein and recovery was more than 85% of the enzyme activity in the crude extract. Glutathione agarose affinity chromatography resulted in a purification factor of about 49 and chromatofocusing resolved the purified enzyme into two major isoenzymes (pI 8.7 and 7.9) and two minor isoenzymes (pI 8.3 and 6.9). The homogeneity of the purified enzyme was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and gel filtration on Sephadex G-100. The different isoenzymes were composed of a binary combination of two subunits with molecular weight of 29,000 D and 26,000 D to give a native molecular weight of 55,000 D. The substrate specificities of the major camel kidney glutathione S-transferase isoenzymes were determined towards a range of substrates. 1-chloro-2,4-dinitrobenzene was the preferred substrate for all the isoenzymes. Isoenzyme III (pI 7.9) had higher specific activity for ethacrynic acid and isoenzyme II (pI 8.3) was the only isoenzyme that exhibited peroxidase activity. Ouchterlony double-diffusion analysis with rabbit antiserum prepared against the camel kidney enzyme showed fusion of precipitation lines with the enzymes from camel brain, liver and lung and no cross reactivity was observed with enzymes from kidneys of sheep, cow, rat, rabbit and mouse. Different storage conditions have been found to affect the enzyme activity and the loss in activity was marked at room temperature and upon repeated freezing and thawing.
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PMID:A rapid purification procedure for camel kidney glutathione S-transferase. 311 33


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