• Proceedings of the Korean Nutrition Society Conference
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• 2002.11a
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• pp.73-82
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• 2002

The low molecular weight zinc-binding protein metallothionein (U) contains 32% cysteine and has been shown to efficiently scavenge hydroxyl radicals in vitro. MT expression is induced by oxidative stress and an antioxidant role for this protein has therefore been proposed. This review mainly focuses on the evidence for this role arising from studies using genetically modified animals and cells which either over- or under-express MT. Despite some considerable disparity of results in the literature, reported studies do generally support an antioxidant role. Nevertheless, oxidant stress at non-physiological treatment levels has been the preferred experimental model and there is little information about the role of MT in physiological oxidative stress. Although it is presumed that the mechanism by which MT has an antioxidant effect involves oxidation of cysteinal thiols, it is possible that zinc release from MT is in itself an important signalling factor.

• BMB Reports
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• v.29 no.5
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• pp.436-441
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• 1996

The palmitoyl acyl carrier protein (ACP) specific thioesterase (EC 3.1.2.14) from Iris pseudoacorus was purified and characterized. The thioesterase which was very unstable in relatively high salt concentrations was eluted using a co-gradient of Triton X-100 and low concentration of KCl or Na-phosphate from Q-Sepharose, DEAE-Sepharose, and hydroxyapatite chromatography. SDS-PAGE analysis showed a single band with a molecular weight of 35,000. The native molecular weight of approximately 37,000 was estimated by Sephacryl S-200 chromatography, indicating that the enzyme is a monomer. The thioesterase activity was inhibited about 75% and 50% by N-ethylmaleimide (2 mM) and phenylmethylsulfonyl fluoride (2 mM). respectively. The N-ethylmaleimide-inactivation was protected by sodium palmitate but the inactivation with phenylmethylsulfonyl fluoride was not protected. Oxidation of thiols by 2 mM 5.5'-dithio-bis-(2-nitrobenzoic acid) resulted in 65% inactivation of the enzyme. These results suggest that a cysteinyl residue is essential to the catalytic reaction of the enzyme. The enzyme activity was increased by sodium citrate and also by $Cu^{2+}$

• BMB Reports
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• v.40 no.3
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• pp.382-395
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• 2007

The herb, Cajanus indicus L, is well known for its hepatoprotective action. A 43 kD protein has been isolated, purified and partially sequenced from the leaves of this herb. A number of in vivo and in vitro studies carried out in our laboratory suggest that this protein might be a major component responsible for the hepatoprotective action of the herb. Our successive studies have been designed to evaluate the potential efficacy of this protein in protecting the hepatic as well as renal tissues from the sodium fluoride (NaF) induced oxidative stress. The experimental groups of mice were exposed to NaF at a dose of 600 ppm through drinking water for one week. This exposure significantly altered the activities of the antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione reductase (GR) and the cellular metabolites such as reduced glutathione (GSH), oxidized glutathione (GSSG), total thiols, lipid peroxidation end products in liver and kidney compared to the normal mice. Intraperitoneal administration of the protein at a dose of 2 mg/kg body weight for seven days followed by NaF treatment (600 ppm for next seven days) normalized the activities of the hepato-renal antioxidant enzymes, the level of cellular metabolites and lipid peroxidation end products. Post treatment with the protein for four days showed that it could help recovering the damages after NaF administration. Time-course study suggests that the protein could stimulate the recovery of both the organs faster than natural process. Effects of a known antioxidant, vitamin E, and a non-relevant protein, bovine serum albumin (BSA) have been included in the study to validate the experimental data. Combining all, result suggests that NaF could induce severe oxidative stress both in the liver and kidney tissues in mice and the protein possessed the ability to attenuate that hepato-renal toxic effect of NaF probably via its antioxidant activity.

• BMB Reports
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• v.41 no.9
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• pp.657-663
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• 2008

The present study was undertaken to investigate the protective role of taurine (2-aminoethanesulfonic acid) against cadmium (Cd) induced oxidative stress in murine erythrocytes. Cadmium chloride ($CdCl_2$) was chosen as the source of Cd. Experimental animals were treated with either $CdCl_2$ alone or taurine, followed by Cd exposure. Cd intoxication reduced hemoglobin content and the intracellular Ferric Reducing/Antioxidant Power of erythrocytes, along with the activities of antioxidant enzymes, glutathione content, and total thiols. Conversely, intracellular Cd content, lipid peroxidation, protein carbonylation, and glutathione disulphides were significantly enhanced in these cells. Treatment with taurine before Cd intoxication prevented the toxin-induced oxidative impairments in the erythrocytes of the experimental animals. Overall, the results suggest that Cd could cause oxidative damage in murine erythrocytes and that taurine may play a protective role in reducing the toxic effects of this particular metal.

• The Journal of Natural Sciences
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• v.17 no.1
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• pp.13-29
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• 2006

Most redox-active proteins have thiol-bearing cysteine residues that are sensitive to oxidation. Cysteine thiols oxidized to sulfenic acid are generally unstable, either forming a disulfide with a nearby thiol or being further oxidized to a stable sulfinic acid, which have been viewed as an irreversible protein modification. However, recent studies showed that cysteine residues of certain thiol peroxidases (Prxs) undergo reversible oxidation to sulfinic acid and the reduction reaction is catalyzed by sulfiredoxin (Srx1). Specific Cys residues of various other proteins are also oxidized to sulfinic acid ($Cys-So_2H$). Srxl is considered one of the oxidant proteins with a role in signaling through catalytic reduction of oxidative modification like in the reduction of glutathionylation, a post-translational, oxidative modification that occurs on numerous proteins. In this study, the role of sulfiredoxin in cellular processes, was investigated by studying its interaction with other proteins. Through the yeast two-hybrid system (Y2HS) technique, we have found that Ams1 is a potential and novel interacting protein partner of Srxl. $\alpha$-mannosidase (Ams1) is a resident vacuolar hydrolase which aids in recycling macromolecular components of the cell through hydrolysis of terminal, non-reducing $\alpha$-D-mannose residues. It forms an oligomer in the cytoplasm and under nutrient rich condition and is delivered to the vacuole by the Cytoplasm to Vacuole (Cvt) pathway. Aside from the role of Srxl as a catalyst in the reduction of cysteine sulfenic acid groups, it may play a completely new function in the cellular process as indicated by its interaction with Ams1 of the yeast Saccharomyces cerevisiae.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.6
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• pp.1499-1505
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• 2007

Peroxynitrite ($ONOO^-$) is a reactive oxidant formed from superoxide anion radical (${\cdot}\;O_2-$) and nitric oxide (NO), which can oxidize cellular components such as essential protein, non-protein thiols, DNA, low-density lipoproteins and membrane phospholipids. ${\cdot}\;O_2-$ and $ONOO^-$ have contributed to the pathogenesis of diseases such as stroke, heart disease, Alzheimer's disease and atherosclerosis. Because of damaging effects of ${\cdot}\;O_2-$ and $ONOO^-$ oxidants, Vespae Nidus, which has been known to strengthen the kidneys to preserve the vital energy. was tested as a potential specific scavenger of those oxidants. In this study, the viability of Vespae Nidus (1, 10, 50 g/ml) to scavenge ${\cdot}\;O_2-$, NO, $ONOO^-$ and so to protect cells against tert-butylhydroxyperoxide (t-BHP) induced cell death was tested. The levels of ${\cdot}\;O_2-$ and $ONOO^-$ were detected by staining with DCFH-DA and DHR 123, respectively. Protein expression levels of COX-2, iNOS and $NF{-\kappa}B$ were assayed by western blot. Vespae Nidus blocked t-BHP-induced cell death in a dose-dependent fashion. Vespae Nidus inhibited t-BHP-induced production of ${\cdot}\;O_2-$, NO and $ONOO^-$ in YPEN cells. The lipid peroxide level was increased and glutathione level was decreased in lipopolysaccharide (LPS)-treated ICR mouse, whereas the ones in the Vespae Nidus-administered group were regulated beneficially. Vespae Nidus inhibited the expression of COX-2, iNOS and NF-κB (p65 and p50) genes in LPS-treated ICR mouse. The present study suggests that Vespae Nidus is a powerful antioxidant and promotes cellular defense activity by scavenging the toxic oxidants such as ${\cdot}\;O_2-$ and $ONOO^-$.

• Archives of Pharmacal Research
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• v.27 no.7
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• pp.683-692
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• 2004

Curcumin (diferuloylmethane) is a major naturally-occurring polyphenol of Curcuma species, which is commonly used as a yellow coloring and flavoring agent in foods. Curcumin has shown anti-carcinogenic activity in animal models. Curcumin possesses anti-inflammatory activity and is a potent inhibitor of reactive oxygen-generating enzymes such as lipoxygenase/cyclooxygenase, xanthine dehydrogenase/oxidase and inducible nitric oxide synthase; and an effective inducer of heme oxygenase-1. Curcumin is also a potent inhibitor of protein kinase C(PKC), EGF(Epidermal growth factor)-receptor tyrosine kinase and LĸB kinase. Subsequently, curcumin inhibits the activation of NF(nucleor factor)KB and the expressions of oncogenes including c-jun, c-fos, c-myc, NIK, MAPKs, ERK, ELK, PI3K, Akt, CDKs and iNOS. It is proposed that curcumin may suppress tumor promotion through blocking signal transduction path-ways in the target cells. The oxidant tumor promoter TPA activates PKC by reacting with zinc thiolates present within the regulatory domain, while the oxidized form of cancer chemopreventive agent such as curcumin can inactivate PKC by oxidizing the vicinal thiols present within the catalytic domain. Recent studies indicated that proteasome-mediated degradation of cell proteins playa pivotal role in the regulation of several basic cellular processes including differentiation, proliferation, cell cycling, and apoptosis. It has been demonstrated that curcumin-induced apoptosis is mediated through the impairment of ubiquitin-proteasome pathway. Curcumin was first biotransformed to dihydrocurcumin and tetrahydrocurcumin and that these compounds subsequently were converted to monoglucuronide conjugates. These results suggest that curcumin-glucuronide, dihydrocurcumin-glucuronide, tetrahydrocurcumin-glucuronide and tetrahydrocurcumin are the major metabolites of curcumin in mice, rats and humans.

• Nutritional Sciences
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• v.6 no.1
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• pp.12-19
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• 2003

The measurement of the total antioxidant capacity (TAC) of human plasma has been widely applied in nutritional science, for example to evaluate the antioxidant contribution of dietary components and to study, although indirectly, the bioavailability of dietary antioxidants. Several methods have been proposed for the measurement of TAC, most of them based on the ability of plasma to withstand the oxidative damage induced by aqueous radicals. Although plasma contains both hydrophilic and lipophilic antioxidants that interact through extensive cross-talk in most of the methods employed for the TAC measurement, the hydrophilic antioxidants such as ascorbic acid, uric acid, and protein thiols mainly contribute to the total antioxidant plasma capacity (almost 70%) while lipophilic antioxidants embedded in the lipoproteins (carotenoids, a-tocopherol, ubiquino1-10) participate only in a negligible amount (less than 5%). The present paper reviews the analytical methods used to assess the TAC and in particular focuses on new approaches that are capable of distinguishing the antioxidant capacity of both the aqueous and lipid compartments of plasma. The general principle of the method as well as some in vitro and ex vivo applications will be discussed within the text.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.383-391
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• 2014

Biotin-S-S-Phosphine was designed and synthesized as a potential tool for a proteomic study of O-GlcNAcmodified proteins. This reagent features a disulfide linker between a triarylphosphine moiety, which allows selective conjugation to azide-containing proteins, and a biotin moiety that can allow easy isolation through its strong affinity toward avidin-coated solid beads. The disulfide linkage within this reagent can allow the easy release of the bound molecules of interest, which is difficult to achieve when a biotin:avidin pair is used alone, by reducing the disulfide bond of the reagent with DTT. Preliminary in vitro biological assays with azidelabeled and unlabeled cell lysates and a pure protein Nup62 showed that the Biotin-S-S-Phosphine reagent is highly reactive toward the free thiol groups of proteins. When a molecular tool with a disulfide linker is applied to the enrichment of the molecules of interest from other species, it is important to block the free-thiols of the sample using exhaustive alkylation prior to the Staudinger ligation reactions to restore the bioorthogonal nature of this reaction.

• Parasites, Hosts and Diseases
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• v.54 no.3
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• pp.247-252
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• 2016

This study was conducted to investigate the occurrence of oxidative stress in the heart tissue of rats infected with Trypanosoma evansi. Rats were divided into 2 groups (A and B) with 12 animals each, and further subdivided into 4 subgroups (A1 and A2, 6 animals/each; and B1 and B2, 6 animals/each). Animals in the groups B1 and B2 were subcutaneously inoculated with T. evansi. Thiobarbituric acid reactive substances (TBARS), superoxide dismutase activity (SOD), glutathione S-transferase activity (GST), reduced glutathione activity (GSH), and non-protein thiols (NPSH) in the heart tissue were evaluated. At day 5 and 15 post-infection (PI), an increase in the TBARS levels and a decrease in the SOD activity (P<0.05) were observed. GSH and GST activities were decreased in infected animals at day 15 PI (P<0.05). Considering the proper functioning of the heart, it is possible that the changes in the activity of these enzymes involved in the oxidative stress may be related, at least in part, in the pathophysiology of rats infected with T. evansi.