• BMB Reports
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• v.28 no.1
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• pp.17-20
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• 1995

Thioredoxin reductase is a flavoprotein oxidoreductase catalyzing the reduction of a cystine disulfide in thioredoxin. Thioredoxin, in turn, can reduce disulfide bonds in other proteins and serves as a reducing agent in enzymatic reactions such as those of ribonucleotide reductase and methionine sulfoxide reductase. In this work thioredoxin reductase was found to directly reduce DTNB in the absence of thioredoxin. This new reactivity of E. coli thioredoxin reductase was produced by relatively high concentrations of univalent cations such as $Na^+$, $K^+$, $Li^+$, and ${NH_4}^+$, and it appeared with the oxidation of NADPH. These results indicate that E. coli thioredoxin reductase may be slightly modified by univalent cations, and the modified enzyme directly reacts with DTNB. This DTNB-reducing activity offers a new assay method for E. coli thioredoxin reductase.

• Parasites, Hosts and Diseases
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• v.47 no.4
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• pp.421-424
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• 2009

Malaria parasites adapt to the oxidative stress during their erythrocytic stages with the help of vital thioredoxin redox system and glutathione redox system. Glutathione reductase and thioredoxin reductase are important enzymes of these redox systems that help parasites to maintain an adequate intracellular redox environment. In the present study, activities of glutathione reductase and thioredoxin reductase were investigated in normal and Plasmodium berghei-infected mice red blood cells and their fractions. Activities of glutathione reductase and thioredoxin reductase in P. berghei-infected host erythrocytes were found to be higher than those in normal host cells. These enzymes were mainly confined to the cytosolic part of cell-free P. berghei. Full characterization and understanding of these enzymes may promise advances in chemotherapy of malaria.

• BMB Reports
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• v.44 no.10
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• pp.692-697
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• 2011

To investigate the pathways of oxidoreductases in plants, 2 key components in thioredox systems i.e. thioredoxin h (Trx h) and NADPH-dependent thioredoxin reductase (NTR) genes were first isolated from tomatoes (Solanum lycopersicum). Subsequently, the coding sequences of Trx h and NTR were inserted into pET expression vectors, and overexpressed in Escherichia coli. In the UV-Visible spectra of the purified proteins, tomato Trx h was shown to have a characteristic 'shoulder' at ~290 nm, while the NTR protein had the 3 typical peaks unique to flavoenzymes. The activities of both proteins were demonstrated by following insulin reduction, as well as DTNB reduction. Moreover, both NADPH and NADH could serve as substrates in the NTR reduction system, but the catalytic efficiency of NTR with NADPH was 2500-fold higher than with NADH. Additionally, our results reveal that the tomato Trx system might be involved in oxidative stress, but not in cold damage.

• Journal of Microbiology
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• v.44 no.4
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• pp.461-465
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• 2006

The occurrence of thioredoxin reductase (NAD(P)H: oxidized-thioredoxin reductase, EC 1.6.4.5, TrxR) in five mesophilic species of Deinococcus was investigated by PAGE. Each species possessed a unique TrxR pattern, for example, a single TrxR characterized D. radiopugnans while multiple forms of TrxR occurred in other Deinococcal spp. Most of TrxRs occurring in Deinococcus showed dual cofactor specificity, active with either NADH or NADPH, although the NADPH specific-TrxR was observed in D. radiophilus and D. proteolytic us.

• BMB Reports
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• v.32 no.2
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• pp.203-209
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• 1999

Three-week grown Arabidopsis thaliana leaves were wounded by cutting whole leaves with a razor blade into pieces (about$3\;mm\;{\times}\;3\;mm$) submerged in various solutions, and incubated in a growth chamber for 24 h. We measured and compared activities of several enzymes such as phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), thioredoxin, thioredoxin reductase, thioltransferase, glutathione reductase, and $NADP^+$ -malate dehydrogenase. PAL activity was decreased in $HgCl_2$-, $CdCl_2$-, and glyphosate-treated leaf slices, and could not be detected after treatment with $CdCl_2$. TAL activity was found to be maximal in the $CdCl_2$-treated leaf slices. Activity of thioredoxin, a small protein known as a cofactor of ribonucleotide reductase and a regulator of photosynthesis, was significantly increased in the $CdCl_2$-treated leaf slices, while thioredoxin reductase activity was maximal in the $HgCl_2$-treated leaf slices. Thioltransferase and glutathione reductase activities were significantly decreased in the $HgCl_2$-treated leaf slices. $NADP^+$ -malate dehydrogenase activity remained relatively constant after the chemical treatments. Our results strongly indicate that sulfhydryl-related and phenylpropanoid-synthesizing enzyme activities are affected by chemical treatments such as hydrogen peroxide, heavy metals, and glyphosate.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3515-3516
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• 2010

• Archives of Pharmacal Research
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• v.28 no.9
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• pp.1065-1072
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• 2005

The nascent thyroglobulin (Tg) multimer molecule, which is generated during the initial fate of Tg in ER, undergoes the rapid reductive depolymerization. In an attempt to determine the depolymerization process, various types of Tg multimers, which were generated from deoxy­cholate-treated/reduced Tg, partially unfolded Tg or partially unfolded/reduced Tg, were subjected to various GSH (reduced glutathione) reducing systems using protein disulfide isomerase (PDI), glutathione reductase (GR), glutaredoxin or thioredoxin reductase. The Tg multimers generated from deoxycholate-treated/reduced Tg were depolymerized readily by the PDI/GSH system, which is consistent with the reductase activity of PDI. The PDI/GSH-induced depolymerization of the Tg multimers, which were generated from either partially unfolded Tg or partially unfolded/reduced Tg, required the simultaneous inclusion of glutathione reductase, which is capable of reducing glutathionylated mixed disulfide (PSSG). This suggests that PSSG was generated during the Tg multimerization stage or its depolymerization stage. In particular, the thioredoxin/thioredoxin reductase system or glutaredoxin system was also effective in depolymerizing the Tg multimers generated from the unfolded Tg. Overall, under the net GSH condition, the depolymerization of Tg multimers might be mediated by PDI, which is assisted by other reductive enzymes, and the mechanism for depolymerizing the Tg multimers differs according to the type of Tg multimer containing different degrees and types of disulfide linkages.

• Journal of Life Science
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• v.32 no.1
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• pp.63-69
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• 2022

The thioredoxin reductase (TrxR) system is essential for cell survival and function by playing a pivotal role in maintaining homeostasis of cellular redox and regulating signal transduction pathways. The TrxR system comprises thioredoxin (Trx), TrxR, and nicotinamide adenine dinucleotide phosphate. Trx reduced by the catalytic reaction of the TrxR enzyme reduces downstream proteins, resulting in protection against oxidative stress and regulation of cell differentiation, growth, and death. Cancer cells survive by improving their intracellular antioxidant capacity to eliminate excessively generated reactive oxygen species (ROS) due to infinite cell proliferation and a high metabolic rate. Therefore, cancer cells have high dependence and sensitivity to antioxidant systems, suggesting that focusing on TrxR, a representative antioxidant system, is a potential strategy for cancer therapy. Several studies have revealed that TrxR is expressed at high levels in various types of cancers, and research on anticancer activity targeting the TrxR system is increasing. In this review, we discuss the feasibility and value of the TrxR system as a strategy for anticancer activity research by examining the relationship between the function of the intracellular TrxR system and the development and progression of cancer, considering the anticancer activity and mechanism of TrxR inhibitors.

• BMB Reports
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• v.31 no.6
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• pp.554-559
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• 1998

Activities of glutathione- and thioredoxin-related enzymes and phenylpropanoid-synthesizing enzymes were measured and compared in the developing leaves of Arabidopsis thaliana. Phenylalanine ammonia-lyase activity is maximal in the leaves of 2-wk-grown Arabidopsis. Tyrosine ammonia-lyase activity is maximal in the leaves of 3-wk-grown and 4-wk-grown Arabidopsis. Activity of thioitransferase, an enzyme involved in the reduction of various disulfide compounds, is higher in younger leaves than in older ones. A similar pattern was obtained in the activity of thioredoxin, a small protein known as a cofactor of ribonucleotide reductase and a regulator of photosynthesis. Activity of glutathione reductase is also higher in the younger leaves. Malate debydrogenase activity remains relatively constant during the development of Arabidopsis leaves. The results offer preliminary information for further approach to elucidate the mechanism of growth-dependent variations of these enzymes.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3169-3170
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• 2012