• BMB Reports
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• v.40 no.3
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• pp.412-418
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• 2007

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is an unique antioxidant enzyme that directly reduces lipid hydroperoxides in biomembranes. In the present work, the entire encoding region for Oryza sativa PHGPx was expressed in Escherichia coli M15, and the purified fusion protein showed a single band with 21.0 kD and pI = 8.5 on SDS- and IFE-PAGE, respectively. Judging from CD and fluorescence spectroscopy, this protein is considered to have a well-ordered structure with 12.2% $\alpha$-helix, 30.7%$\beta$-sheet, 18.5% $\delta$-turn, and 38.5% random coil. The optimum pH and temperature of the enzyme activity were pH 9.3 and 27$^{\circ}C$. The enzyme exhibited the highest affinity and catalytical efficiency to phospholipid hydroperoxide employing GSH or Trx as electron donor. Moreover, the protein displayed higher GSH-dependent activity towards t-Butyl-OOH and $H_2O_2$. These results show that OsPHGPx is an enzyme with broad specificity for hydroperoxide substrates and yielded significant insight into the physicochemical properties and the dynamics of OsPHGPx.

• Archives of Pharmacal Research
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• v.26 no.7
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• pp.521-525
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• 2003

Phytochemical works on the aerial parts of Aster oharai (Compositae) led to the isolation of a new sesquiterpene hydroperoxide, 7$\alpha$-hydroperoxy-3, 11-eudesmadiene (2) and seven known compounds, teucdiol B (1), $\alpha$-spinasterol (3), oleanolic acid (4), $\alpha$-spinasterol 3-Ο-$\beta$-D-glucopyranoside (5), methyl 3,5-di-Ο-caffeoyl quinate (6), 3,5-di-Ο-caffeoylquinic acid (7), 3,4-di-Ο-caffeoylquinic acid (8). The chemical structures of 1-8 were established by chemical and spectroscopic methods. Compound 2 showed cytotoxicity against cultured human tumor cell lines in vitro, SK-OV-3 (ovarian), SK-MEL-2 (skin melanoma), and HCT15 (colon) with $ED_{50}$ values ranging from 3.86-17.21 $\mu$g/mL.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.517-520
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• 2001

Fossil fuels such as coal and crude oil contain various organic sulfur compounds. Combustion of these fuels emit sulfur oxides which are considered as msjor air pollutants causing acid rain problem. Among various organic sulfur compounds, aromatic sulfur compounds of thiophenes which constitute major sulfur fractions of heavy oils are not easily removed by hydrodesulfurization. Many peroxidase and hemoproteins are known to oxidize dibenzothiophene (DBT) to dibenzothiophene-sulfoxide(DBT - sulfoxide) then dibenzothiophene- sulfone (DBT-sulfone). The oxidation of DBT by the immobilized hemoproteins in n-octane was increased significantly when the hemoproteins were deposited on celites of the particle size between 0.75 - 1.0 mm and a conventional substrates. such as t-butyl hydroperoxide and cumene hydroperoxide. In anhydrous organic solvents with log P values larger than 4.0 DBT was completely oxidized by cumene hydroperoxide catalyzed by cytochrome c deposited on celites.

• Tribology and Lubricants
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• v.16 no.1
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• pp.22-26
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• 2000

In this paper, the fuction of Zinc-dialkyldithiophosphate (ZnDTP) as an oxidation ingibitor of mineral oils was investigated and compared with 2,6-Di-tert-Butyl-4-Methylphenol (DBMP). Oxidation tests were conducted using an oxygen absorption apparatus. ZnDTP showedanti-oxidation property, and length of induction period prolonged by increasing ZnDTP concentration. The anti-oxidation property of ZnDTP was simmilar to that with DBMP. The amount of hydroperoxide decomposition ability with ZnDTP was much greater than that with DBMP, But the rate constant of radical scavenging with ZnDTP was less than that with DBMP. The anti-oxidation property of ZnDTP seems to by both synergy effect of hydroperoxide decomposition ability and radical scavenging ability.

• Journal of the Korean Wood Science and Technology
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• v.23 no.3
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• pp.23-27
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• 1995

Several characteristic results of physical and optical properties of paper treated by UV light were obtained in the previous papers(Kim et al. 1988). In this paper, folding endurance and brightness of paper prepared by spraying photostabilizer were examined in order to elucidate photodegradation phenomena, UV light absorber and radical scavenger were most effective in preventing of folding endurance decrease. These results may be indicated that depolymerization of cellulose and hemicellulose chains leading to degradation of paper mechanical properties mainly caused by radical reaction. Ineffective hydroperoxide decomposer may be explained because of auto-oxidation reactions before forming stable compound from hydroperoxide.

• Natural Product Sciences
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• v.14 no.4
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• pp.244-248
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• 2008

It is well known that excessive production of reactive oxygen species (ROS) leads to oxidative stress, loss of cell function, and ultimately apoptosis or necrosis. To search for natural antioxidants able to modulate cellular oxidative stress, we investigated the protective effect of ethanol extracts of 17 medicinal plants selected from the preliminary antioxidant screening on tert-butyl hydroperoxide (t-BuOOH)-induced oxidative stress in human keratinocytes. The result showed that extracts of the four plants, Distylium racemosum, Astilbe chinensis, Cercis chinensis and Sapium japonicum, exhibited significant cytoprotective activity (over 50% protection) against t-BuOOH-induced cellular injury.

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.05a
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• pp.161-161
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• 2001

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is an antioxidant selenoenzyme which interacts directly with and diminishes peroxidized phospholipids, cholesterol and cholesteryl ester in tissues. PHGPx activity appears in most tissues, but is especially high in testis. In testis, PHGPx level decreases in hypophysectomized rats but is partially restored after gonadotropin treament.(omitted)

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.05a
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• pp.163-163
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• 2001

Selenium (Se) is an essential micronutrient for mammals and its biological functions are mediated by selenoprotein. In tissues, Se is incorporated into the selenoprotein by recognition of the UGA codon as a stop codon for selenoprotein. Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is an antioxidant selenoprotein that belongs to the superfamily of selenium-dependent peroxidase.(omitted)

• YAKHAK HOEJI
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• v.46 no.1
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• pp.1-5
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• 2002

A new cytotoxic triterpene hydroperoxide (3) was isolated from the methylene chloride extract of the aerial part of Youngia japonica together with four known triterpenes (1, 2, 4 and 5). Their structures were identified by means of physico-chemical and spectral data to be $\beta$-amyrin acetate (1), taraxasterol (2), 2l$\alpha$-hydroperoxy-taraxasterol (3), oleanolic acid (4) and ursolic acid (5). Compounds 3 and 5 showed moderate cytotoxicity against five tumor cell lines.

• YAKHAK HOEJI
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• v.37 no.1
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• pp.95-99
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• 1993

Peroxidase activity of cytochrome P-450 was examined using N, N-dimethylaniline (NDA) as a substrate and cumene hydroperoxide (CHP) as an oxidant. The initial rates of the N-demethylation for varied concentrations of NDA (0.05-0.5 mM) by P-450 at different fixed concentrations of CHP (0.02-0.2 mM) were determined. The results suggest that P-450 proceeds its peroxidative reaction by the rapid equilibrium random bi bi mechanism to form a ternary complex with substrate and oxidant as an active intermediate.