Showing papers on "GPX3 published in 1976"
TL;DR: It is proposed that glutathione functions to stabilise enzymes of the Calvin cycle, and it may also act to keep ascorbic acid in chloroplasts in the reduced form.
Abstract: Both glutathione and an NADPH-dependent glutathione reductase are present in spinach (Spinacia oleracea L.) chloroplasts. It is proposed that glutathione functions to stabilise enzymes of the Calvin cycle, and it may also act to keep ascorbic acid in chloroplasts in the reduced form.
2,351 citations
817 citations
TL;DR: The kinetic behavior or the purified lung soluble gluthathione peroxidase followed a ping-pong-like mechanism; the enzyme first reduced the lipid hydroperoxide substrate to the corresponding hydroxy fatty acid, then was regenerated to the native form by reduced glutathione.
330 citations
TL;DR: It appears, therefore, that glutathione peroxidase activity must exert its effect on this system by preventing free radical attack on the polyunsaturated membrane lipids in the first place.
254 citations
TL;DR: The catalytic properties of transfer enzyme AA are very similar to those of transferase B although the two proteins differ in their ability to bind bilirubin and other ligands, in their amino acid composition, and in their immunological properties.
175 citations
TL;DR: The detection of neurological disorders in patients with inherited deficiencies in glutathione synthesis indicates the importance of this tripeptide in brain function.
Abstract: Publisher Summary Glutathione is the most ubiquitous peptide found in living cells. It plays an important role as a coenzyme in several enzymic reactions. The enzymic reactions of the synthesis and degradation of glutathione are linked in a cyclic process called “γ-glutamyl cycle.” The cycle functions in amino acid transport. Pyrrolidone carboxylate formed by cyclization of the γ-glutamyl moiety of γ-glutamyl amino acids in a reaction of the γ-glutamyl cycle is accepted as a normal intermediate of mammalian metabolism. The detection of neurological disorders in patients with inherited deficiencies in glutathione synthesis indicates the importance of this tripeptide in brain function. Glutathione has two structural features responsible for much of its biochemistry: the sulfhydryl group (because of cysteine) and the γ-glutamyl bond (the bond linking cysteine to glutamate). The sulfhydryl group is responsible for most of the catalytic and reactive properties of glutathione.
123 citations
Journal Article•
TL;DR: It is suggested that vitamin E prevents the accumulation of lipid peroxide, but not controls the level of peroxide scavenging system such as superoxide dismutase, glutathione peroxidase and catalase.
Abstract: The activities of superoxide dismutase, glutathione peroxidase, catalase and xanthine oxidase were simultaneously studied in vitamin-E deficient and -supplemented rat liver and also measured the lipid peroxide content in liver. The lipid peroxide content of vitamin E-deficient rat liver, estimated by thiobarbituric acid, increased as compared with that of vitamin E-supplemented rat liver. No marked changes of activities of superoxide dismutase, glutathione peroxidase and catalase were observed, but the activity of xanthine oxidase which is strong superoxide generator increased in vitamin E-deficient rat liver. These results suggest that vitamin E prevents the accumulation of lipid peroxide, but not controls the level of peroxide scavenging system such as superoxide dismutase, glutathione peroxidase and catalase.
77 citations
TL;DR: Sheep vesicular gland microsomes have been found to have an unusual peroxidase activity with a wide peroxide specificity and capable of oxidizing cofactors of prostaglandin synthetase.
74 citations
TL;DR: This form of enzymatic regulation is proposed, and it is proposed that it inhibits by destroying an essential activator of the oxygenase which forms the PGs and thromboxanes.
Abstract: BIOSYNTHESIS of prostaglandins (PGs) from unsaturated fatty acid precursors involves a complex sequence of reactions that seem to proceed rapidly in response to physiological stimuli. Studies in vitro have revealed a capacity for biosynthesis greater than would be expected from measures of tissue content1,2 or daily prostaglandin (PG) production3. Biosynthesis requires release of esterified precursor from tissue lipids4,5, and control of the hydrolytic event may be a major means of controlling PG biosynthesis (for example, in brain6 or spleen7). Another possible type of regulation is control of cyclo-oxygenase activity. Many chemical agents have been examined as modifiers of the PG-forming oxygenase (for example, reviews in refs 8 and 9). The enzyme can be inhibited by fatty acids10 although they appear only in limited amounts in the cytosol. In addition, inhibition of the oxygenation reaction has been observed in vitro with added glutathione peroxidase (GSP) and reduced glutathione (GSH)11–14. We have further investigated this form of enzymatic regulation, and propose that it inhibits by destroying an essential activator of the oxygenase which forms the PGs and thromboxanes.
60 citations
54 citations
TL;DR: In this study, rats tolerant to ozone maintained higher activities of GP, GR and G6PD, and higher levels of GSH in the lungs following excessive exposure, suggesting the adaptive response of this potentially protective enzymic system in the lung of ozone-tolerant rats may be partly responsible for their resistance against lethal exposure.
Abstract: THE health hazard of ozone, the principal oxidant air pollutant of photochemical smog, has been well documented1–3. One of the notable features of ozone toxioity is the development of tolerance. When animals are exposed to a single sublethal dose of ozone they become resistant to subsequent lethal exposure. This tolerance phenomenon has been demonstrated in several species, and the effect has been shown to persist for well over one month3–6. One of its toxic effects has been attributed to its oxidative nature, and, more specifically, the initiation of lipid peroxidation7–9. Glutathione peroxidase (GP), which uses the reducing equivalent of reduced glutathione (GSH) to catalyse the decomposition of toxic hydroperoxides, and metabolically related enzymes glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PD), have been suggested as a key mechanism for protection of cellular components from deleterious effects of hydroperoxides10,11. The activities of these enzymes have been found to increase in the lungs of rats exposed to chronic levels of ozone9, and in tissues of rats subjected to other oxidative stress12,13. Thus changes in the activities of these enzymes seem to be related in some way to the defence mechanism against peroxidative damage. In this study, rats tolerant to ozone maintained higher activities of GP, GR and G6PD, and higher levels of GSH in the lungs following excessive exposure. The adaptive response of this potentially protective enzymic system in the lungs of ozone-tolerant rats may therefore be partly responsible for their resistance against lethal exposure.
Journal Article•
TL;DR: The possible role of peroxidase in these two estrogen-sensitive tissues is discussed and evidence provided against the proposal that this enzyme is always associated with growth processes.
TL;DR: Cytochemical and ultrastructural analysis of wild-type cells of Saccharomyces cerevisiac shows that cytochrome c peroxidase is localized between the membranes of the cristae, that is, in the intracristal space, and positioned appropriately within the organelle to act as an alternate terminal oxidase for the respiratory chain.
Abstract: Cytochemical and ultrastructural analysis of wild-type cells of Saccharomyces cerevisiac, grown aerobically in a glucose-limited chemostat, shows that cytochrome c peroxidase is localized between the membranes of the cristae, that is, in the intracristal space. This enzyme is thus positioned appropriately within the organelle to act as an alternate terminal oxidase for the respiratory chain. The proximity of the peroxidase to major sites of generation of its two substrates may account for the small leakage of hydrogen peroxide from yeast mitochondria, as compared with the larger outflow from mammalian mitochondria.
TL;DR: The ratios of the levels of the metabolites involved suggested that the reactions of the glucose-6-phosphate dehydrogenase and of the glutathione reductase operate dependent on the redox state of the triphosphopyridine nucleotides.
Abstract: In the corneal epithelium the levels of the oxidized and reduced glutathione, the oxidized and reduced triphosphopyridine nucleotide, the glucose-6-phosphate and the 6-phosphogluconate were investigated. The in vivo steady state levels were defined by preparation procedures and by the energy state of the adenosine phosphate system. The ratios of the levels of the metabolites involved suggested that the reactions of the glucose-6-phosphate dehydrogenase and of the glutathione reductase operate dependent on the redox state of the triphosphopyridine nucleotides.
Journal Article•
TL;DR: Actinomycin D administered in a dose of 0.5 mg/kg simultaneously with selenite prevents the rise in the enzyme activity and relative weight of the liver caused only by a single injection of selenium in the same dose.
Abstract: Sodium selenite 24h after its single administration to rats causes an increase in the activity of glutathione peroxidase and glutathione reductase in the liver tissue. 6 h after the selenium administration the enzymes activity does not differ from the control. Doses of 0.15, 0.3, 0.5 and 1 mg of selenium per 1 kg of the animal weight were investigated. 0.3 mg proved to be the least effective dose. An increase in the enzyme activity after administering 0.5 mg of selenium is retained for 6 days and 14 days after it does not differ from the control. The liver relative weight 24 h after administration of 0.5 mg of selenium per 1 kg of animal weight proved to be higher but three days later it did not differ from the control. After administering selenium in a dose of 1 mg/kg the liver relative weight was higher for 6 days. Actinomycin D administered in a dose of 0.5 mg/kg simultaneously with selenite prevents the rise in the enzyme activity and relative weight of the liver caused only by a single injection of selenium in the same dose.
Journal Article•
TL;DR: A single introduction of vitamin E and D,L-methionine to rats kept on the vivarium ration or their addition to protein-free diet separately does not affect the glutathionperoxidase and glutath ionreductase activities in the liver.
Abstract: A single introduction of vitamin E and D,L-methionine to rats kept on the vivarium ration or their addition to protein-free diet separately does not affect the glutathionperoxidase and glutathionreductase activities in the liver. A simultaneus introdyction of the vitamin and methionine causes an increase in the glutathionperoxidase activity, without changing the glutathionreductase activity. Vitamin E prevents from increasing the glutathionperoxidase and glutathionreductase activities due to selenium. Propyl gallate produces no such effect.
TL;DR: It is possible that proliferation of peroxidasomes might permit a new approach to the treatment of infections illnesses, since the full function of neutrophils depends on the state of the peroxidaomes (azurophils).
Abstract: Peroxidasomes have been characterized as organelles, distinct from lysosomes, containing the enzyme peroxidase, which is a system for generating hydrogen peroxide and oxidizable cofactors (halides or thiocyanates) [I, 2]. A hypothesis has been advanced [3] on the sim~ ilarity of peroxidasomes with peroxisomes containing catalase which may work peroxidatively at low concentrations of hydrogen peroxide [4]. It might be supposed that one or other chemical agents act equally on peroxisomes and peroxidasomes. The proliferation of peroxisomes by various cells is known to occur under the influence of clofibrate [5-9]. It is possible that proliferation of peroxidasomes might permit a new approach to the treatment of infections illnesses, since the full function of neutrophils depends on the state of the peroxidasomes (azurophils).