• Molecules and Cells
• /
• 제22권2호
• /
• pp.220-227
• /
• 2006

Oxidative alteration of mitochondrial cytochrome c has been linked to disease and is one of the causes of proapoptotic events. We have investigated the modification of cytochrome c by $H_2O_2$. When cytochrome c was incubated with $H_2O_2$, oligomerization of the protein increased and the formation of carbonyl derivatives and dityrosine was stimulated. Radical scavengers prevented these effects suggesting that free radicals are implicated in the $H_2O_2$-mediated oligomerization. Oligomerization was significantly inhibited by the iron chelator, deferoxamine. During incubation of deoxyribose with cytochrome c and $H_2O_2$, damage to the deoxyribose occurred in parallel with the release of iron from cytochrome c. When cytochrome c that had been exposed to $H_2O_2$ was analyzed by amino acid analysis, the tyrosine, histidine and methionine residues proved to be particularly sensitive. These results suggest that $H_2O_2$-mediated cytochrome c oligomerization is due to oxidative damage resulting from free radicals generated by a combination of the peroxidase activity of cytochrome c and the Fenton reaction of free iron released from the oxidatively-damaged protein.

• 생명과학회지
• /
• 제19권3호
• /
• pp.343-348
• /
• 2009

벼도열병균은 벼의 주요 병해인 벼도열병의 원인균이다. 식물병원균의 침입 시 식물체로부터 발생하는 ROS는 식물의 방어기작으로 중요하며, 특히 아미노산의 하나인 methionine은 ROS에 의해 산화되어 methionine sulfoxide로 변화될 수 있다. 식물병원균은 식물체로 부터의 ROS에 의한 산화반응을 회피하기 위해 methionine sulfoxide reductase B (MSRB)와 같은 항산화 효소를 가지는데 본 연구에서는 벼도열병균에서의 MSRB 유전자를 동정하고 분자적 특성을 살펴보았다. MSRB 유전자는 벼도열병균의 게놈 상에 단일 유전자로 존재하며 과산화수소 처리에 의해 유전자발현이 다소 증가하는 경향을 보였다. 이러한 결과로 MSRB 유전자는 벼도열병균의 항산화 기작에 관여할 가능성이 높다고 판단된다.

• 한국환경성돌연변이발암원학회지
• /
• 제26권1호
• /
• pp.7-11
• /
• 2006

Reactive oxygen species (ROS) are known to cause oxidative modification of DNA, proteins, lipids and small cellular molecules and are associated with tissue damage and are the contributing factors for diabetes, inflammation, aging, cancer, arteriosclerosis, and hypertension. We screened the anti-oxidative effect on V79-4 hamster lung fibroblast cells induced by hydrogen peroxide with eleven extracts of combined medicinal plants. Dancheonhwankakambang and Samikangyabtang were found to show the scavenging activities of DPPH radical and intracellular reactive oxygen species, which is measured by dichlorodihydrofluorescin diacetate method (DCHF-DA).

• Bulletin of the Korean Chemical Society
• /
• 제25권5호
• /
• pp.711-714
• /
• 2004

Peroxynitrite enters erythrocytes through band 3 anion exchanger and oxidizes cytosolic proteins therein. As a protein associated with band 3, carbonic anhydrase II may suffer from peroxynitrite-induced oxidative damages. Esterase activity of carbonic anhydrase II decreased as the concentration of peroxynitrite increased. Neither hydrogen peroxide nor hypochlorite affected the enzyme activity. Inactivation of the enzyme was in parallel with the release of zinc ion, which is a component of the enzyme's active site. SDS-PAGE of peroxynitrite-treated samples showed no indication of fragmentation but non-denaturing PAGE exhibited new bands with lower positive charges. Western analysis demonstrated that nitration of tyrosine residues increased with the peroxynitrite concentration but the sites of nitration could not be determined. Instead MALDI-TOF analysis identified tryptophan-245 as a site of nitration. Such modification of tryptophan residues is responsible for the decrease in tryptophan fluorescence. These results demonstrate that peroxynitrite nitrates tyrosine and tryptophan residues of carbonic anhydrase II without causing fragmentation or dimerization. The peroxynitrite-induced inactivation of the enzyme is primarily due to the release of zinc ion in the enzyme's active site.

• 생약학회지
• /
• 제28권4호
• /
• pp.275-279
• /
• 1997

Fruits of Arctium lappa L. (Compositae), which has been used as the antiinflammatory, detoxifying and diuretic agents in the folk remedies, was examined on the in vitro oxidation of human low density lipoprotein (LDL). Several lines of evidence indicate that oxidized LDL (Ox-LDL) may promote atherogenesis. Hence. The role of antioxidants in the prevention of LDL oxidation needs to be determined. The activity of fractions of Arctii Fructus treated with oxidized LDL which was incubated with $16\;{\mu}M$ of $Cu^{2+}$ for metal catalyzed oxidation was investigated. The BuOH fraction (4\;ppm) inhibited the oxidative modification of LDL as evidenced by a decrease in the lipid peroxide content (thiobarbituric acid reacting substances activity), the negative charge of LDL (electrophoretic mobility) and increase of the vitamine E content.

• Molecules and Cells
• /
• 제39권1호
• /
• pp.72-76
• /
• 2016

Cell death pathways such as apoptosis can be activated in response to oxidative stress, enabling the disposal of damaged cells. In contrast, controlled intracellular redox events are proposed to be a significant event during apoptosis signaling, regardless of the initiating stimulus. In this scenario oxidants act as second messengers, mediating the post-translational modification of specific regulatory proteins. The exact mechanism of this signaling is unclear, but increased understanding offers the potential to promote or inhibit apoptosis through modulating the redox environment of cells. Peroxiredoxins are thiol peroxidases that remove hydroperoxides, and are also emerging as important players in cellular redox signaling. This review discusses the potential role of peroxiredoxins in the regulation of apoptosis, and also their ability to act as biomarkers of redox changes during the initiation and progression of cell death.

• Elastomers and Composites
• /
• 제25권4호
• /
• pp.273-279
• /
• 1990

The graft polymerization of 2-hydroxyethylmethacrylate(HEMA) and vinyltriethoxysilane(VTES) onto styrene-butadiene-styrene block copolymer(SBS) was carried out in toluene, with radical initiator such as benzoyl peroxide(BPO) and 2, 2'-azo-bis-isobutyronitrile(AIBIN) under nitrogen atmosphere. The degree of grafting was increased with the increases of the reaction temperature and time. And the effeciency of BPO was superior to that of AIBN. The mechanical properties and molecular weight of graft products were measured and the applicability as adhesive of plasticized PVC leather was examined.

• Nutritional Sciences
• /
• 제8권4호
• /
• pp.262-267
• /
• 2005

Reactive oxygen species can be generated in the skin by hair dyeing. The aim of this study was to find out the effects of the oxidative-type hair dye application in young women on the antioxidant systems. We investigated the lipid peroxide levels, glutathione (GSH) levels, and the antioxidant enzyme activities including superoxide dismutase (SOD), glutathione peroxidase (GSHPx) in plasma and erythrocytes and catalase (CAT) in erythrocytes, and DNA damages in lymphocytes. Also, plasma concentrations of antioxidant vitamins, vitamin A and E, were measured and the correlations between various antioxidant parameters and oxidative damages were evaluated The antioxidant enzyme activities in plasma (GSHPx) and in erythrocytes (SOD and CAT) were decreased significantly after hair dyeing. 1be lipid peroxide and GSH levels were not affected in both plasma and erythrocytes. No significant difference was found in the concentrations of both vitamin A and E between before and after hair dyeing. However, DNA damages expressed as the tail extent moment (TEM) and tail length (TL) were significantly (p<0.001) increased. The plasma vitamin E concentration was correlated with DNA damages (TEM: r=-0.590, p<0.01 and TL: r=-0.533. p<0.01) and RBC SOD activity (r=0.570, p<0.05). In turn, RBC SOD activity was significantly correlated with both plasma MDA levels (r=-0.412, p<0.05) and DNA damages (TM: r=-0.546, p<0.01, TL: r=-0.493, p<0.01). Our results demonstrated that the exposure to hair dyeing produced lymphocyte DNA damage and modification of the antioxidant enzyme activities. Also, there were very strong associations between plasma vitamin E concentration, RBC SOD activity and DNA damage induced by hair dyeing. It suggests that the antioxidant status of a subject is likely to be related to the extent of the harmful effects caused by hair dyeing.

• 멤브레인
• /
• 제23권3호
• /
• pp.220-225
• /
• 2013

친수성 단량체를 polyvinylidene fluoride (PVDF) 분리막 표면에 열중합으로 lamination하여 분리막을 친수화하였다. 친수화 처리 후 접촉각은 $95^{\circ}$에서 $55^{\circ}$까지 감소하였고 수투과량은 10배 이상 증가하였으며 bovine serum albumin (BSA) 흡착량은 1/4 수준으로 감소하였다. 열중합 공정에서 각 공정변수별 영향을 조사하였고 이를 최적화하였다. 단량체 중 dimethyl oxobuthyl acrylamide (DOAA)가 친수성이 높아 다른 단량체에 비하여 친수화 효과가 우수하였다. 단량체의 농도가 증가함에 따라 성능이 향상되었으나 30 wt% 이상의 경우 homopolymerization을 유발하여 성능을 저하시켰다. 개시제로 사용되었던 azobis (isobutyronitrile)(AIBN)의 활성 온도 범위가 benzoyl peroxide (BPO)의 활성온도 범위보다 넓기 때문에 높은 친수화 효율을 나타내었다. 개시제를 먼저 도포시켜주고 단량체를 나중에 첨가하는 2단계 lamination 방식이 일괄 공급하는 1단계 방식보다 친수화도는 크게 향상됐지만 pore blocking현상이 나타나면서 순수투과도는 매우 감소하였다.

• 한국수소및신에너지학회논문집
• /
• 제27권3호
• /
• pp.298-305
• /
• 2016

In this study, we treated pitch-based activated carbon fibers (ACFs) in hydrogen peroxide using electron beam (E-beam) irradiation to improve nitrogen monoxide (NO) sensing ability as an electrode material of gas sensor. The specific surface area of ACFs treated by E-beam irradiation with 400 kGy increased from $885m^2/g$ (pristine) to $1160m^2/g$ without any changes in structural property and functional group. The increase in specific surface area of the E-beam irradiated ACFs enhanced NO gas sensing properties such as response time and sensitivity. When the ACFs irradiated with 400 kGy, response time was remarkably reduced from 360 s to 210 s and sensitivity was increased by 4.5%, compared to the pristine ACFs. These results demonstrate convincingly that surface modification of ACFs using E-beam in hydrogen peroxide solution can enhance textural properties of ACFs and NO gas sensing ability of gas sensor at room temperature.