Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activities of the anti-oxidative enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase were studied in rat tissues to determine the ability of detergents both to solubilize the enzymes and also to stabilize enzyme activity. Rat brain, heart and liver were homogenized in 0.1M KCl, 0.1% sodium dodecyl sulfate, 0.1% lubrol, or 0.1% cetyl-trimethylammonium bromide. In general lubrol was more effective than the other solutions in solubilizing GPx and catalase. Lubrol and 0.1M KCl were equally effective in solubilizing SOD. The highest enzyme activities were (1) SOD: 2484 ng/mg (brain), 2501 ng/mg (heart), and 5586 ng/mg (liver); (2) GPx: 224 mU/mg (brain), 1870 mU/mg (heart), and 7332 mU/mg (liver); (3) catalase: 2.8 mU/mg (brain), 10.6 mU/mg (heart), and 309 mU/mg (liver). While cetyl trimethylammonium bromide is marginally better than sodium dodecyl sulfate in solubilizing active enzyme, neither ionic detergent has any advantage over lubrol or 0.1M KCl. For catalase and GPx, enzyme activity loss with time is biphasic. After initial, rapid activity loss (1-5 days for GPx and 7-10 days for catalase) the differences noted among the homogenizing solutions disappear and very little if any activity loss is noted over the next 2-3 weeks. For catalase and GPx, only baseline enzyme activity from t = 0-3 weeks is found in the most chaotropic solution, 0.1% sodium dodecyl sulfate while biphasic activity loss is most pronounced in 0.1% lubrol. These results may indicate active GPx and catalase species stabilized by a lipid-like environment. Correlating in vitro catalase or GPx measurements with in vivo anti-oxidative protection may underestimate tissue defences.
Mol Cell Biochem 1991 Sep 18
PMID:Stability of the anti-oxidative enzymes in aqueous and detergent solution. 178 73

Great excitement was elicited in the field of selenium biochemistry in 1986 by the parallel discoveries that the genes encoding the selenoproteins glutathione peroxidase and bacterial formate dehydrogenase each contain an in-frame TGA codon within their coding sequence. We now know that this codon directs the incorporation of selenium, in the form of selenocysteine, into these proteins. Working with the bacterial system has led to a rapid increase in our knowledge of selenocysteine biosynthesis and to the exciting discovery that this system can now be regarded as an expansion of the genetic code. The prerequisites for such a definition are co-translational insertion into the polypeptide chain and the occurrence of a tRNA molecule which carries selenocysteine. Both of these criteria are fulfilled and, moreover, tRNASec even has its own special translation factor which delivers it to the translating ribosome. It is the aim of this article to review the events leading to the elucidation of selenocysteine as being the 21st amino acid.
Mol Microbiol 1991 Mar
PMID:Selenocysteine: the 21st amino acid. 182 28

In the presence of glutathione (GSH 400 microM), rat hepatocyte homogenates converted 5-hydroperoxyeicosatetraenoic acid (5-HPETE), via the intermediate leukotriene A4, into leukotriene C4 (LTC4) and leukotriene B4 (LTB4); 5-hydroxyeicosatetraenoic acid (5-HETE) was also a prominent product. During a 5-min incubation with 100 microM (13.4 microgram) 5-HPETE, 0.24 ng of LTC4, 15.4 ng of all-trans-LTB4, 4.3 ng of LTB4, and 12.4 micrograms of 5-HETE were formed/mg of protein. In incubations devoid of GSH, 38.6 ng of all-trans-LTB4, 8.8 ng of LTB4, and 2.2 micrograms of 5-HETE were formed/mg of protein, and 3.3 micrograms of intact 5-HPETE could be recovered. The presence of GSH induced a time-dependent rapid depletion of 5-HPETE, paralleled by large increases in the formation of 5-HETE; formation of LTC4 was detected in the presence but not in the absence of GSH. Addition of thiomalic acid (0.1 mM) or penicillamine (0.2 mM), both inhibitors of selenium-dependent GSH peroxidases, increased formation rates of LTC4 by factors of 3 and 2, respectively, whereas the suppressive effects of GSH on the formation of LTB4 were partially reversed. These results suggest that hepatocytes are capable of the simultaneous synthesis of cysteinyl- and dihydroxy-leukotrienes as well as 5-HETE; the availability of the precursor 5-HPETE and the profile of leukotrienes formed are dependent on the GSH concentration and the extent of GSH peroxidase activity.
Mol Pharmacol 1991 Mar
PMID:Transformation of 5-hydroperoxyeicosatetraenoic acid into dihydroxy- and cysteinyl-leukotrienes by rat hepatocytes: effects of glutathione. 184 55

Porphyrias are inherited and acquired diseases of erythroid or hepatic origin, in which there are defects in specific enzymes of the heme biosynthetic pathway. In patients with intermittent acute porphyria and lead poisoning the erythrocytic activities of superoxide dismutase and glutathione peroxidase are reported to be increased. Our studies demonstrated that d-aminolevulinic acid, a heme precursor accumulated in both diseases, undergoes enolization at pH less than 7.0 before it autoxidizes. The autoxidation of d-aminolevulinic acid, in the presence or absence of oxyhemoglobin has been proposed as a source of oxy and carbon-centred radicals in the cells of intermittent acute porphyria and saturnism carriers. Thus, the increased levels of antioxidant enzymes can be viewed as an intracellular response against the deleterious effects of these extremely reactive species.
Mol Cell Biochem 1991 Apr 24
PMID:Free radicals involvement in neurological porphyrias and lead poisoning. 185 46

In seven rabbits subjected to suprarenal aortic coarctation hypertension, the segments above and below the coarctation were tested for the antioxidant defences (i.e. acid-soluble thiol compounds, selenium-dependent and selenium-independent glutathione peroxidase, glutathione reductase, glutathione transferase) and thiobarbituric acid-reactive substances. Seven sham-operated rabbits served as controls. Systolic blood pressure proximal to the ligature increased significantly with respect to pre-operative values after 16 days (117 +/- 8.3 vs 71.7 +/- 5.2 mmHg, P less than 0.05), while pressure distal to the ligature remained normotensive. Higher values of acid-soluble thiol compounds, thiobarbituric acid-reactive substances and increased activities of selenium-dependent glutathione peroxidase, glutathione reductase and glutathione transferase were assayed in the suprarenal with respect to the subrenal segment in both groups. However, the values of the upper segments were more elevated in the experimental group than in controls, but no differences were observed in the lower segments. Glutathione peroxidase activity assayed with cumene hydroperoxide was higher than the activity assayed with hydrogen peroxide in the hypertensive segments, but no differences were detected in the substenotic and control segments. Furthermore, an isoenzymatic form of glutathione transferase, analogous to rat 8-8 glutathione transferase isoenzyme, was detected by immunodiffusion in the hypertensive aorta. The following conclusions may be drawn: (1) a biochemical gradient in glutathione-related enzymes, acid-soluble thiol compounds and thiobarbituric acid-reactive substances between the proximal and distal aorta seems to exist in control rabbits; (2) suprarenal aortic coarctation induces a significant increase in glutathione-related antioxidant defences and thiobarbituric acid-reactive substances of the hypertensive aortic wall.
J Mol Cell Cardiol 1991 Jun
PMID:Aortic glutathione-related antioxidant defences in rabbits subjected to suprarenal aortic coarctation hypertension. 194 85

H69AR is a multidrug-resistant small cell lung cancer cell line derived from a drug-sensitive cell line, H69, by selection in doxorubicin. It is cross-resistant to a wide variety of natural product-type antineoplastic agents but does not overexpress P-glycoprotein. In the present study, the levels of GSH and GSH-related enzymes in the H69AR cell line were determined and compared with those found in H69 cells. Unlike other drug-resistant cell lines, GSH levels were diminished 6-fold in H69AR cells (0.67 +/- 0.28 microgram/mg of protein), compared with H69 cells (4.23 +/- 1.17 micrograms/mg of protein) (p less than 0.01). This unusually low level of GSH may explain the pronounced collateral sensitivity of H69AR cells to buthionine sulfoximine (BSO), an inhibitor of the rate-limiting enzyme in GSH biosynthesis (ID50 of 4.4 microM BSO for H69AR cells versus ID50 of 300 microM BSO for H69 cells). BSO did not enhance doxorubicin cytotoxicity in the H69AR cell line, despite further depletion of GSH. GSH-reductase (EC 1.6.4.2) activity was elevated 2-fold in H69AR cells, compared with sensitive H69 cells (75.34 +/- 14.94 versus 38.62 +/- 5.06 nmol of NADPH/min/mg of protein) (p less than 0.05). Both selenium-dependent and -independent GSH-peroxidase (EC 1.11.1.9) activities were unchanged in the resistant H69AR cell line, compared with its parent cell line. gamma-Glutamyl transpeptidase (EC 2.3.2.2) activity was 5-fold elevated in H69AR cells, compared with H69 cells (2.50 +/- 0.44 versus 0.46 +/- 0.21 nmol of p-nitroaniline/min/mg of protein) (p less than 0.01), whereas GSH-S-transferase (EC 2.5.1.18) activity was 10-fold higher (201.98 +/- 43.62 versus 19.77 +/- 1.72 nmol of 1-chloro-2,4-dinitrobenzene/min/mg of protein in H69AR and H69 cells, respectively) (p less than 0.01). The GSH-S-transferases from both cell lines were purified by affinity chromatography and immunoblot analysis identified the GSH-S-transferases as belonging to the anionic pi class. GSH-S-transferases from the mu or alpha classes were not detectable in either cell line. In conclusion, marked differences in GSH levels and the activities of three of four GSH-related enzymes were observed between the multidrug-resistant H69AR cell line and its parent cell line. Further study is required to determine whether these changes are causally related to the development of drug resistance in this model system.
Mol Pharmacol 1990 Feb
PMID:Alterations in glutathione and glutathione-related enzymes in a multidrug-resistant small cell lung cancer cell line. 196 21

The effects of a subclinical fascioliasis at various stages of its development (at week 3, 6 and 9 after infection by oral administration of 20 metacercariae of Fasciola hepatica) in rats were determined on the activity of enzymes involved in liver metabolism of glutathione and on the subunit pattern of cytosolic glutathione S-transferase. The parasitic pathology was ascertained by clinical observation of the rats and at autopsy. Hepatic microsomal cytochrome P-450 content was significantly decreased in infected rats by week 3 and 6 post-infection. Not correlatively, the catalytic activities of glutathione S-transferase towards 1-chloro-2,4-dinitrobenzene and 1,2-dichloro-4-nitrobenzene were significantly lowered in last stages of the experimental fascioliasis (by week 6 and 9 post-infection). These decreases were correlated to that of subunit 1 as determined by means of high-performance liquid chromatography of cytosolic proteins whereas subunit 6 could also be decreased. Fascioliasis did not alter cytosolic glutathione, glutathione reductase and glutathione peroxidase activities or plasma glutathione S-transferase activity accepting 1-chloro-2,4-dinitrobenzene as the substrate.
Mol Biochem Parasitol 1991 Feb
PMID:Differential inhibition of rat hepatic glutathione S-transferase isoenzymes in the course of fascioliasis. 205 25

Oxidative stress induced by cumene hydroperoxide was studied in cultured neonatal rat myocytes. A progressive increase of irreversible cell injury as determined by leakage of the cytoplastic enzyme alpha-hydroxybutyrate dehydrogenase (alpha-HBDH) from the cells was noted at concentrations ranging from 25-100 microM cumene hydroperoxide (incubation time 90 min). Cumene hydroperoxide-induced damage was reduced or prevented by several compounds: the application of Trolox C, a water-soluble vitamin E analogue, and of phospholipase A2 inhibitors chlorpromazine and (to a lesser extent) quinacrine prevented alpha-HBDH release. ICRF-159, a chelator of divalent cations, ascorbic acid, a potent antioxidant, and the cysteine protease inhibitor leupeptin did not reduce the cumene hydroperoxide-induced cytotoxicity. Detoxification of hydroperoxides by the glutathione peroxidase system results in an increased flux through the pentose phosphate shunt and loss of NADPH. Glucose inhibited the cumene hydroperoxide-induced alpha-HBDH release, probably by replenishing NADPH. These results indicate that cumene hydroperoxide, after exhaustion of the glutathione system, induces irreversible injury in cultured myocytes by a mechanism that depends to a large extent on deterioration of cellular membranes caused by lipid peroxidation and phospholipase activation.
J Mol Cell Cardiol 1990 Oct
PMID:Prevention of cumene hydroperoxide induced oxidative stress in cultured neonatal rat myocytes by scavengers and enzyme inhibitors. 209 37

The influence of membrane polyunsaturated fatty acid (PUFA) composition on lactate production, energy status, enzyme leakage and cell defences against oxygen free radical production was studied in cultured rat ventricular myocytes during hypoxia and reoxygenation. After 4 days in a conventional serum-supplemented medium, the cardiomyocytes were incubated for 24 h in synthetic media containing either linoleate and arachidonate (SM6 Medium) or linolenate and eicosapentaenoate (SM3 Medium) as unique source of PUFA. The fatty acid n-6/n-3 ratio of phospholipid was 13.1 in SM6 cells and 0.9 in SM3 cells. Hypoxia induced an increase in lactate production, severe decreases in ATP and ADP, leakage of cellular lactate dehydrogenase and reduction of superoxide dismutase and glutathione peroxidase activities. Reoxygenation of hypoxic cells reduced lactate production to normal aerobic values and allowed slight resynthesis of ATP from AMP. However, lactate dehydrogenase release was not stopped by reoxygenation, and decreases in superoxide dismutase and glutathione peroxidase activities were not avoided. The majority of the biochemical parameters measured during normoxia, hypoxia and reoxygenation were not significantly affected by changes in the fatty acid composition of membrane phospholipids, except for reduced superoxide dismutase activity which appeared earlier in SM3 cells during hypoxia. We conclude that the sarcolemmal PUFA composition of cultured rat ventricular myocytes does not significantly influence altered cell metabolism elicited by hypoxia and reoxygenation.
J Mol Cell Cardiol 1990 Oct
PMID:Influence of phospholipid polyunsatured fatty acid composition on some metabolic disorders induced in rat cardiomyocytes by hypoxia and reoxygenation. 209 39

The contribution of lung glucose-6-phosphate dehydrogenase (G-6-PD) activity to pulmonary antioxidant defenses was investigated in the isolated perfused rabbit lung using dehydroepiandrosterone (DHEA), a specific steroidal inhibitor of G-6-PD. Infusion of xanthine oxidase (0.002 U/ml) generated moderate lung edema as measured by increased lung weight and lung lavage albumin content. Infusion of DHEA caused an augmentation of xanthine oxidase-induced lung edema. Hydrostatic factors did not participate in the worsened lung edema because mean pulmonary artery pressures were similar in both experimental groups. Incubation of lung tissue in vitro with DHEA demonstrated ablation of tissue G-6-PD activity without decreasing catalase, glutathione peroxidase, or superoxide dismutase activity. It was concluded that DHEA is a specific inhibitor of lung G-6-PD, and that G-6-PD provides an important antioxidant defense mechanism in preventing oxidant-induced lung injury.
Am J Respir Cell Mol Biol 1990 Mar
PMID:Inhibition of rabbit lung glucose-6-phosphate dehydrogenase by dehydroepiandrosterone augments oxidant injury. 213 22


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