• Title/Summary/Keyword: redox system

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Evaluation of Cytotoxicity to Rat Platelets by Menadione-Glutathione Conjugate and its Stability in Biological Assay System (Menadione의 대사체인 Menadione-Glutathione Conjugate(MEN-SG)가 흰쥐 혈소판에 미치는 세포독성의 평가 및 MEN-SG의 안정성에 관한 연구)

  • Seo, Dong-Chul;Chung, Sun-Hwa;Lee, Joo-Young;Kim, Mee-Jeong;Chung, Jin-Ho
    • Toxicological Research
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    • v.11 no.2
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    • pp.295-302
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    • 1995
  • Menadione-ghitathione conjugate (MEN-SG), a metabolite of menadione, is known to be a redoxcycler in rat hepatocyte subcellular fraction. Therefore, it was assumed that MEN-SG could exert cytotoxlclty to ral platelets, another target tissue of menadione. We first synthesized MEN-SG, the identity of which was verified by mass, $^1{H}$-NMR and UV-visible spectra. In addition, the stability of MEN-SG was investigated in biological assay system. MEN-SG was degraded in a time-dependent manner in DMSO which had been used as a vehicle and thus, tris-HCl buffer was used as a vehicle of MEN-SG despite the low solubility in it. Perchloric acid as well as platelets itself did not affect the stability of MEN-SG. Our next attempt was the evaluation of cytotoxicity of MEN-SG in rat platelets. MEN-SG did not induce cytotoxicity to rat platelets measured by two different methods, LDH release and turbidity changes. The extents of oxygen consumption by MEN-SG in intact platelets were significantly lower than those by menadione, though it had been observed that oxygen consumptions by menadione and MENSG were similar in subcellular fractioas of platelets. These results suggest that MEN-SG is not toxic to rat platelets despite its redox cycling capacity and glutathione conjugation reaction of menadione could be regarded as a detoxification process.

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Effect of Electrochemical Redox Reaction on Biochemical Ammonium Oxidation and Chemical Nitrite Oxidation

  • Jeon, Bo-Young;Seo, Ha-Na;Kang, Seung-Won;Park, Doo-Hyun
    • Journal of Microbiology and Biotechnology
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    • v.20 no.3
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    • pp.485-493
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    • 2010
  • A modified graphite felt electrode with neutral red (NR-electrode) was shown to catalyze the chemical oxidation of nitrite to nitrate under aerobic conditions. The electrochemically oxidized NR-electrode (EO-NR-electrode) and reduced NR-electrode (ER-NR-electrode) catalyzed the oxidation of $1,094{\pm}39$ mg/l and $382{\pm}45$ mg/l of nitrite, respectively, for 24 h. The electrically uncharged NR-electrode (EU-NR-electrode) catalyzed the oxidation of $345{\pm}47$ mg/l of nitrite for 24 h. The aerobic bacterial community immobilized in the EO-NR-electrode did not oxidize ammonium to nitrite; however, the aerobic bacterial community immobilized in the ER-NR-electrode bioelectrochemically oxidized $1,412{\pm}39$ mg/l of ammonium for 48 h. Meanwhile, the aerobic bacterial community immobilized on the EU-NR-electrode biochemically oxidized $449{\pm}22$ mg/l of ammonium for 48 h. In the continuous culture system, the aerobic bacterial community immobilized on the ER-NR-electrode bioelectrochemically oxidized a minimal $1,337{\pm}38$ mg/l to a maximal $1,480{\pm}38$ mg/l of ammonium to nitrate, and the community immobilized on the EU-NR-electrode biochemically oxidized a minimal $327{\pm}23$ mg/l to a maximal $412{\pm}26$ mg/l of ammonium to nitrate every two days. The bacterial communities cultivated in the ER-NR-electrode and EU-NR-electrode in the continuous culture system were analyzed by TGGE on the $20^{th}$ and $50^{th}$ days of incubation. Some ammonium-oxidizing bacteria were enriched on the ER-NR-electrode, but not on the EU-NR-electrode.

Variation in Nitrate Contamination of Shallow Groundwater in a Farmland in Gyeonggi-do, Korea (경기도 지역 농경지의 천부 지하수 내 질산염 오염특성과 변화)

  • Lee, Eun-Jae;Woo, Nam-Chil;Lee, Byung-Sun;Kim, Yang-Bin
    • Economic and Environmental Geology
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    • v.41 no.4
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    • pp.393-403
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    • 2008
  • Hydrogeochemistry of groundwater was studied in order to identify the influence of cow manure, distributed to a farmland as organic fertilizer, on nitrate concentrations in shallow groundwater and its spatio-temporal variations. From monitoring wells, water levels were measured using automatic data loggers, and water samples collected and analyzed in Feb., April, June and Oct. 2007. The average electric conductivity and concentration of nitrate in the groundwater show the highest levels in April and decline in subsequent sampling times. Decreases in dissolved oxygen(DO) and nitrate concentrations from April to Oct. and corresponding increases in $HCO_3$ concentrations indicate denitrification processes by microorganisms. Spatial variation of nitrate concentration appeared to be affected by the redox conditions of groundwater controlled by geochemical reactions of Mn, Fe and DOC contents.

Enhanced Synthesis of Active rPA in the Continuous Exchange Cell-free Protein Synthesis [CECF] System utilizing Molecular Chaperones (분자 샤페론을 사용한 연속확산식 무세포단백질 발현 시스템에서의 재조합 Plasminogen Activator의 효율적 발현)

  • Park, Chang-Gil;Kim, Tae-Wan;Choi, Cha-Yong;Kim, Dong-Myung
    • KSBB Journal
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    • v.21 no.2
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    • pp.118-122
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    • 2006
  • In this report, we describe that the use of GroEL/GroES-enriched S30 extract remarkably enhances the solubility and enzymatic activity of cell-free synthesized rPA, which requires the correct formation of 9 disulfide bonds for its biological activity. We found that the stable maintenance of redox potential is necessary, but not sufficient for the optimal expression of active rPA. In a control reaction without using additional molecular chaperones, most of the rPA molecules were aggregated almost instantly after their expression and thus failed to exhibit the enzymatic activity. However, by the use of GroEL/GroES-enriched extract, combined with IAM-treatment, approximately $30{\mu}g/ml$ of active rPA was expressed in the cell-free synthesis reaction. This result not only demonstrates the efficient production of complex proteins, but also shows the control and flexibility offered by the cell-free protein synthesis system.

The Effect of CaO2 Application on the Change of Sedimentary Phosphorus Fraction and Water Quality (CaO2 적용에 따른 퇴적물의 P fraction 변화와 수질에 미치는 영향)

  • Kim, Beom-geun;Khirul, Md Akhte;Kwon, Sung-Hyun
    • Journal of Environmental Science International
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    • v.28 no.5
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    • pp.511-520
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    • 2019
  • This study was investigated to improve the phosphorus release and water quality by transformation of sedimentary P fraction for application of $CaO_2$. For the experiment, 0.5% (w/w) of $CaO_2$ was homogenized in the sediment and incubated with the control for 20 days. The analytical results showed that pH increased with $CaO_2$ and redox potential (ORP) was improved in the sediment of the reactor. The growth rate of chlorophyll-a was lower in the $CaO_2$ reactor and Dissolved Oxygen (DO) of overlying water maintained higher than that of the control. Total phosphorus (T-P) concentration in the overlying water increased from the initial concentration to 0.304mg/L in the control at 20 days. The reactor of $CaO_2$ was lowered by 29.3%. Ex-P, Fe-P and Ca-P in sediment P fraction were increased with the $CaO_2$. The formation of bound Fe-P and Ca-P in the sediments seemed to control the release of P by removing the Soluble Reactive Phosphorus (SRP) presented in the pore water. From the result, this indicated that the reduction of P release from the sediments seems to be effective in suppressing the eutrophication of P and improving the oxygen condition in the water quality with the application of $CaO_2$.

Recent Research Trends in Thioredoxin Reductase-targeted Anticancer Therapy (Thioredoxin reductase를 표적으로 하는 항암 최신 연구 동향)

  • Hwangbo, Hyun;Lee, Hyesook;Cheong, JaeHun;Choi, Yung Hyun
    • 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.

Geochemical Study on the Mobility of Dissolved Elements by Rocks-$CO_2$-rich waters Interaction in the Kangwon Province (강원도 지역 탄산수와 암석간의 반응에 의한 용존 원소들의 유동성에 관한 지구화학적 연구)

  • 최현수;고용권;윤성택;김천수
    • Economic and Environmental Geology
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    • v.35 no.6
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    • pp.533-544
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    • 2002
  • In order to investigate the relative mobility (RM) of dissolved elements during processes controlling major and trace element content, the concentrations of major, minor and trace elements were reviewed from the previous data of $CO_2$-rich waters and granites from Kangwon Province. The relative mobility of elements dissolved in $CO_2$-rich waters is calculated from $CO_2$-rich water/granite ratio with normalizing by sodium. The results show that gaseous input of magmatic volatile metals into the aquifer is negligible in this study area, being limited by cooling of the rising fluids. Granite leaching by weakly acidic, $CO_2$-charged water is the overwhelming source of metals. Poorly mobile element (Al) is preferentially retained in the solid residue of weathering, while alkalis, alkaline earth and oxo-hydroxo anion forming elements (especially As and U) are mobile and released to the aqueous system. Transition metals display an intermediate behavior and are strongly dependent on either the redox conditions (Fe and Mn) or solid surface-related processes (adsorption or precipitation) (V, Zn and Cu).

Surface Display of Heme- and Diflavin-Containing Cytochrome P450 BM3 in Escherichia coli: A Whole-Cell Biocatalyst for Oxidation

  • Yim, Sung-Kun;Kim, Dong-Hyun;Jung, Heung-Chae;Pan, Jae-Gu;Kang, Hyung-Sik;Ahn, Tae-Ho;Yun, Chul-Ho
    • Journal of Microbiology and Biotechnology
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    • v.20 no.4
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    • pp.712-717
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    • 2010
  • Cytochrome P450 enzymes (P450s) are involved in the synthesis of a wide variety of valuable products and in the degradation of numerous toxic compounds. The P450 BM3 (CYP102A1) from Bacillus megaterium was the first P450 discovered to be fused to its redox partner, a mammalian-like diflavin reductase. Here, we report the development of a whole-cell biocatalyst using ice-nucleation protein (Inp) from Pseudomonas syringae to display a hemeand diflavin-containing oxidoreductase, P450 BM3 (a single, 119-kDa polypeptide with domains of both an oxygenase and a reductase) on the surface of Escherichia coli. The surface localization and functionality of the fusion protein containing P450 BM3 were verified by flow cytometry and measurement of enzymatic activities. The results of this study comprise the first report of microbial cell-surface display of a heme- and diflavin-containing enzyme. This system should allow us to select and develop oxidoreductases containing heme and/or flavins into practically useful whole-cell biocatalysts for extensive biotechnological applications, including selective synthesis of new chemicals and pharmaceuticals, bioconversion, bioremediation, live vaccine development, and biochip development.

Selection of Transgenic Potato Plants Expressing NDP Kinase 2 Gene with Enhanced Tolerance to Oxidative Stress (NDP Kinase 2 유전자를 도입한 산화스트레스 내성 형질전환 감자의 선발)

  • Li, Tang;Kwon, Suk-Yoon;Yun, Dae-Jin;Kwak, Sang-Soo;Lee, Haeug-Soon
    • Journal of Plant Biotechnology
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    • v.31 no.3
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    • pp.191-195
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    • 2004
  • Arabidopsis NDPK2 (AtNDPK2) is a key singaling component that regulate cellular redox state and known to enhance multiple stress tolerance when over-expressed in Arabidopsis plant (Moon et al. 2003). In order to develop transgenic potato plants with enhanced tolerance to multiple stresses, we placed an AtNDPK2 cDNA under the control of a stress-inducible SWPA2 promoter or enhanced CaMV 35S promoter. Transgenic potato plants (cv. Superior and Atlantic) were generated using an Agrobacterium-mediated transformation system and selected on MS medium containing 100 mg/L kanamycin. Genomic Southern blot analysis confirmed the incorporation of AtNDPK2 cDNA into the potato genome. When potato leaf discs were treated with methyl viologen (MV) at 10 $\mu$M, transgenic plants showed higher tolerance to MV than non-transgenic or vector-transformed plants. The NDPK2 transgenic potato plants will be further used for analysis of stress-tolerance to multiple environmental stresses.

The study of characterization of extracted vanadium in waste catalyst for vanadium redox flow battery (폐촉매에서 추출한 바나듐 레독스 흐름전지용 바나듐의 특성 연구)

  • Kang, Ung Il
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.10
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    • pp.598-602
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    • 2018
  • This study examined the characteristics of the waste catalyst used in the petroleum refinery operations. The total pore volume, specific surface area, and average pore size of the spent catalyst used in the petroleum refinery operations were 3.96cc/g, 13.81m2/g, and 1.15A, respectively. The weight loss observed in the range from $25^{\circ}C-700^{\circ}C$ for the spent catalysts using TG and DTA was approximately 23 wt. %. EDS analysis of the waste catalyst sample showed that the five major components were vanadium, nickel, manganese, iron, and copper. The extraction system is attractive for liquid-liquid extraction. In this study, Cynex 272 was used to extract vanadium from waste catalyst. The electrochemical characteristics of the extracted vanadium solution were measured by cyclic voltammetry (CV). As a result, an oxidation / reduction peak appeared, indicating the potential of an electrolytic solution.