Assays of glutathione peroxidase
TL;DR: Fixed-time assay measuring H 2 O 2 consumption and continuous monitoring of Glutathione disulfide (GSSG) formation are cited here.
Abstract: Publisher Summary To determine glutathione peroxidase reliably, some factors of potential pitfall have to be considered, for example, enzymatic side reactions of substrates (especially when crude tissue samples are assayed), high and variable spontaneous reaction rates of substrates, and the peculiar kinetics of the enzyme itself. With the best documented example, the enzyme of bovine red blood cells, ping-pong kinetics with infinite limiting maximum velocities, and Michaelis constants have been established. This means that the generally recommended conditions for determination of enzyme activity––that is, “saturating” concentrations of all substrates, cannot possibly be fulfilled. In consequence, compromises are inevitable in the choice of substrate concentration for the assay and in the definition of the unit of activity. Fixed-time assay measuring H 2 O 2 consumption and continuous monitoring of Glutathione disulfide (GSSG) formation are cited here. The main differences between the assay procedure described and those proposed by others are listed in the chapter. To compare the results obtained by different procedures, appropriate empirical converting factors are also given.
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TL;DR: It is demonstrated that oxidative stress is sensed and transduced by glutathione peroxidase 4 (GPx4) into a-yet-unrecognized cell-death pathway, and the identified pathway reveals promising targets for future therapies.
962 citations
Cites methods from "Assays of glutathione peroxidase"
...Measurement of Glutathione Peroxidase Activity Determination of glutathione peroxidase activity was performed as described (Flohe and Gunzler, 1984)....
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TL;DR: The responsiveness of the Nrf2 pathway may act as a major determinant of susceptibility to tobacco smoke-induced emphysema by upregulating antioxidant defenses and decreasing lung inflammation and alveolar cell apoptosis.
Abstract: Although inflammation and protease/antiprotease imbalance have been postulated to be critical in cigarette smoke-induced (CS-induced) emphysema, oxidative stress has been suspected to play an important role in chronic obstructive pulmonary diseases. Susceptibility of the lung to oxidative injury, such as that originating from inhalation of CS, depends largely on its upregulation of antioxidant systems. Nuclear factor, erythroid-derived 2, like 2 (Nrf2) is a redox-sensitive basic leucine zipper protein transcription factor that is involved in the regulation of many detoxification and antioxidant genes. Disruption of the Nrf2 gene in mice led to earlier-onset and more extensive CS-induced emphysema than was found in wild-type littermates. Emphysema in Nrf2-deficient mice exposed to CS for 6 months was associated with more pronounced bronchoalveolar inflammation; with enhanced alveolar expression of 8-oxo-7,8-dihydro-2'-deoxyguanosine, a marker of oxidative stress; and with an increased number of apoptotic alveolar septal cells--predominantly endothelial and type II epithelial cells--as compared with wild-type mice. Microarray analysis identified the expression of nearly 50 Nrf2-dependent antioxidant and cytoprotective genes in the lung that may work in concert to counteract CS-induced oxidative stress and inflammation. The responsiveness of the Nrf2 pathway may act as a major determinant of susceptibility to tobacco smoke-induced emphysema by upregulating antioxidant defenses and decreasing lung inflammation and alveolar cell apoptosis.
927 citations
Cites methods from "Assays of glutathione peroxidase"
...The lungs were excised (n = 3 per group) and processed as described (21) to measure the activities of NQO1, G6PDH, GPx, Prx, and GSR. GPx activity was measured according to the procedure of Flohe and Gunzler (44)....
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...Flohe, L., and Gunzler, W.A. 1984....
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...ity was measured according to the procedure of Flohe and Gunzler (44)....
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TL;DR: Since the three enzymes of the antioxidant system are susceptible to at least one of the oxidative reactive molecules, in the case of high oxidative stresses such an inhibition could take place, leading to an irreversible autocatalytical process in which the production rate of the oxidants will continuously increase,leading to cell death.
716 citations
TL;DR: Results suggest that Prx enzymes likely play an important role in eliminating peroxides generated during metabolism, and might participate in the signaling cascades of growth factors and tumor necrosis factor-α by regulating the intracellular concentration of H2O2.
693 citations
TL;DR: The results of this systematic study on the in vitro interactions of 7-20 nm spherical silver nanoparticles with HT-1080 and A431 cells can be used to define a safe range of SNP for the intended application as a topical antimicrobial agent after appropriate in vivo studies.
670 citations
References
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TL;DR: The results suggest that GSH-Px B is probably an altered form of the major component, GSH,Px A, or its precursor, and the properties of G SH, which appear to be a tetramer.
338 citations
305 citations
TL;DR: Glutathione peroxidase (GSH:H2O2 oxidoreductase, EC 1.11.1.9) was purified 400-fold from rat liver by fractionation with (NH4)2SO4 and chromatography with DEAE-cellulose, Sepha dex G-200 and Sephadex A-50 in the presence of 0.5 mM GSH.
241 citations
62 citations
TL;DR: In this paper, a Reihe bekannter bestimmungs methoden fur SH-Gruppen wird auf Anwendbarkeit, Zuverlassigkeit and Storanfallig keit gepruft.
Abstract: Eine Reihe bekannter Bestimmungsmethoden fur SH-Gruppen wird auf Anwendbarkeit, Zuverlassigkeit und Storanfalligkeit gepruft. Zu diesem Zweck werden je 18 Verbindungen unterschiedlicher Struktur vergleichend analysiert. Amperometrische Titration mit AgNO3 bei pH 7.4 fuhrt nur bei einigen Verbindungsklassen zu richtigen Ergebnissen. Mit vielen Substanzen ergeben sich reproduzierbare, aber uberstochiometrische Werte. Polarographische Analyse in 0.6 M HClO4 fuhrt zu linearen Eichdiagrammen, deren Steigung von der Molekulgrose abhangt. Photometrische Bestimmung sowohl nach Ellman als auch nach Boyer fuhrt zu verlaslichen Ergebnissen. Beide Methoden bedurfen der Eichung durch eine Substanz mit bekanntem SH-Gehalt. Potentiometrische Bestimmung mit der Ag/AgJ-Elektrode nach Umsetzung mit Jodacetat ist die vorteilhafteste Methode zur Absolutbestimmung des SH-Gehaltes und fuhrt mit allen untersuchten Verbindungen zu gut reproduzierbaren und zu verlassigen Ergebnissen.
10 citations