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Saccharomyces cerevisiae
Published in Yoshikatsu Murooka, Tadayuki Imanaka, Recombinant Microbes for Industrial and Agricultural Applications, 2020
The method presented here is directly applicable to the preparation of glutathione containing isotopes in various positions and is also useful for the preparation of isotopically labeled γ-glutamyl peptides. The isotopically labeled glutathione analogues are being used to examine the substrate specificity and mechanism of action of glutathione reductase, glutathione peroxidase, glyoxalase I, γ-GTP, and glutathione transferases. The enzymatically prepared compounds may also be used as intermediates in the chemical synthesis of additional glutathione and glutathione disulfide analogues.
Biological Responses of Mobile Phone Frequency Exposure
Published in Jitendra Behari, Radio Frequency and Microwave Effects on Biological Tissues, 2019
SOD activity decreases due to the effect of electromagnetic field exposure and CAT activity increases. Glutathione peroxidase (GSH-PX) inactivates hydrogen superoxide and organic hydroxides together with glutathione reductase and glucose-6-dehydrogenase with reduced glutathione. The oxidized glutathione generated is then reduced again by NADPH-dependent glutathione reductase, in the process that maintains the peroxidation continuity (Collonce & Hochstein 1981).
Mechanisms of chemically induced respiratory toxicities
Published in Philippe Camus, Edward C Rosenow, Drug-induced and Iatrogenic Respiratory Disease, 2010
Paraquat is selectively taken up in the lung but this accumulation is not associated with covalent binding, nor have any significant metabolites of paraquat been identified. However, there is general agreement that redox cycling is involved in the pulmonary toxicity of paraquat. Under aerobic conditions, the addition of paraquat to incubations containing lung microsomes and NADPH results in marked increases in NADPH oxidation and oxygen uptake.114 Under anaerobic conditions, paraquat is reduced to a free radical metabolite by NADPH in the presence of lung microsomes115 whereas under aerobic conditions, the oxidation of NADPH is due to the cyclic reduction and re-oxidation of paraquat.116 As a result of these reactions, NADPH is consumed and there is a decrease in the NADPH/NADP + ratio. The reduction is also due in part to the utilization of NADPH as a cofactor for glutathione reductase when oxidized glutathione is regenerated back to reduced glutathione. It has been suggested that glutathione oxidation is mediated through its role as a substrate in the reduction of cellular hydrogen peroxide via glutathione peroxidase, and is consistent with evidence showing paraquat-dependent formation of hydrogen peroxide in lung microsomes.116 However, other studies have suggested that hydrogen peroxide is produced from a reactive oxygen species initially formed from the reaction of oxygen with the paraquat radical.117 It has been demonstrated that the superoxide anion radical, a short-lived oxygen species, is formed by the reduction of oxygen by the paraquat radical. It has subsequently been confirmed that the superoxide is generated from paraquat in lung microsomal incubations.118 The dismutation of superoxide by the enzyme superoxide dismutase can produce hydrogen peroxide, which can also be produced by reduction of superoxide by the paraquat radical. The available evidence thus indicated that several potentially toxic species could be generated from oxygen during the process of reduction and re-oxidation of paraquat.
Chemopreventive effect of troxerutin against hydrogen peroxide-induced oxidative stress in human leukocytes through modulation of glutathione-dependent enzymes
Published in Journal of Toxicology and Environmental Health, Part A, 2021
Bruno Coêlho Cavalcanti, João Batista de Andrade Neto, Antônio Adailson de Sousa Silva, Francisco Stefânio Barreto, José Roberto de Oliveira Ferreira, Hemerson Iury Ferreira Magalhães, Cecília Rocha da Silva, Ícaro Gusmão Pinto Vieira, Nágila Maria Pontes Silva Ricardo, Hélio Vitoriano Nobre Júnior, Manoel Odorico Moraes
Glutathione reductase (GR, EC.1.6.4.2) activity was measured following the method of Goldberg (1983) with minor modifications. Glutathione reductase is required for the NADPH-dependent conversion of oxidized glutathione (GSSG) to reduced glutathione (GSH). Briefly, the reaction mixture contained 1.5 ml 0.1 M PBS (pH 7.3), 0.1 ml 15 mM EDTA, and 0.1 ml 70 mM GSSG. Cell lysate was added and incubated at room temperature for 15 min, after which 0.05 ml 9.6 mM NADPH was added. The exponential decrease of NADPH (absorbance/min) was detected spectrophotometrically at 340 for 3 min. The control was run without GSSG. The activity of GR was expressed as µmoles NADPH oxidized/min/mg of protein.
Phytoremediation and detoxification of xenobiotics in plants: herbicide-safeners as a tool to improve plant efficiency in the remediation of polluted environments. A mini-review
Published in International Journal of Phytoremediation, 2020
Daniele Del Buono, Roberto Terzano, Ivan Panfili, Maria Luce Bartucca
As stated above, another important route of the herbicide detoxification is the conjugation of the xenobiotic with the tripeptide GSH (see 3.2). This reaction is catalyzed by the GSTs, a family of enzymes very active in the phase (ii) of the herbicide metabolism. Safeners can enhance the conjugation of thiocarbamates, chloro-s-triazines, triazinone sulfoxides, chloroacetanilides, diphenylethers, some sulfonylureas, aryloxyphenoxypropionates, thiazolidines, and sulfonamides herbicides with GSH (Jablonkai 2013), either by inducing the activity of GSTs or by elevating the cellular levels of reduced glutathione (GSH) (Farago et al.1994; Kocsy et al.2001). The increase of the glutathione content in plant cells can be promoted by safeners by (i) regulating the activities of the first two enzymes of the assimilatory sulfate reduction in higher plants: ATP sulfurylase (ATPS, E.C. 2.7.7.4) and adenosine-5'-phosphosulfate sulfotransferase (APSSTase) (Farago et al.1994); (ii) regulating the sulfate incorporation into cysteine, e.g. by increasing cysteine synthase (CS, E.C. 4.2.99.8) activity (Hirase and Molin 2001); (iii) activating the key enzymes involved in the biosynthesis of GSH: glutathione synthetase (GS, E.C. 6.3.2.3) and y-glutamylcysteine synthetase (y-ECS, E.C. 6.3.2.2) (Hatzios and Burgos 2004); and (iv) inducing the activity of glutathione reductase (GR, E.C. 1.6.4.2), a NAD(P)H-dependent oxidoreductase which converts oxidized glutathione (GSSG) in reduced glutathione (GSH) (see 3.1.2; Gill et al.2013). At last, it has been demonstrated that the safener-mediated induction of GSH in plant for the high antioxidant potential of this tripeptide, is also functional in counteracting the oxidative stress caused by ROS (see 3.1.2) (Edwards, Brazier-Hicks et al.2005). As reported for Cyt P450, the expression of GST by safeners has been reported not only in graminaceous crops but also in dicotyledonous weeds (e.g. Arabidopsis thaliana) (DeRidder et al.2002).