• Toxicological Research
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• 제23권2호
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• pp.127-133
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• 2007

Metformin is a drug used to lower blood sugar levels in patients with type 2 diabetes via activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK). The primary objective of this study was to investigate whether metformin at the pharmacologically effective concentrations affects the expressions of ${\gamma}$-glutamylcysteine synthetase and phase II antioxidant genes in the H4IIE cell. Treatment of the cells with either metformin or 5-aminoimidazole-4-carboxamide riboside (AICAR) abrogated tert-butylhydroxyquinone (t-BHQ) induction of ${\gamma}$-glutamylcysteine synthetase, a rate limiting enzyme of GSH synthesis. The ability of t-BHQ to induce glutathione S-transferases (GSTs), a major class of phase II detoxifying enzymes that playa critical role in protecting cells from oxidative stress or electrophiles, was also inhibited by the agents. Transcriptional gene repression by metformin was verified by the GSTA2 promoter luciferase assay. Moreover, either metformin or AICAR treatment significantly decreased t-BHQ-dependent induction of other GSTs (i.e., $GST{\mu}$ and $GST{\pi}$ forms). Taken together, our data indicate that metformin treatment may result in the repression of ${\gamma}$-glutamylcysteine synthetase and glutathione S-transferase genes possibly via AMPK activation.

• Preventive Nutrition and Food Science
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• 제4권4호
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• pp.260-264
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• 1999

Korean traditional fermented soy paste (doenjang) prolonged the life span of Balb/c mice injected with the sarcoma-180 cells. The activities of liver enzymes, such as xanthine oxidase, aminopyrine N-demethylase, aniline hydroxylase, ${\gamma}$-glutamylcysteine synthetase, glutathione reductase and glutathione S-transferase (GST), and the contents of lipid peroxide and glutathione were determined from the sarcoma-180 cell injected mice that were treated with methanol extracts from doenjang, miso and soybean. The content of lipid peroxide and the activity of xanthine oxidase in the liver of Balb/c mice which were increased by the transplantation of the sarcoma-180 cells were decreased by treatment with the methanol extract from doenjang. But the activities of aminopyrine N-dementhylase and aniline hydroxylase were not affected by the treatment of methanol extracts from doenjang to the mice injected with the sarcoma-180 cells. The content of glutathione, the activities of glutamylcysteine synthetase, glutathione reductase and glutathione S-transferase decreased by the injection of the sarcoma-180 were recovered considerably by the treatment of the methanol extract from doenjang.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.61-61
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• 2003

We have cloned the CGR1 gene encoding glutathione reductase (GR) which catalyzes the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH) from Candida albicans. The cgr1/cgr1 mutants were not viable when CaMAL2 promoter repressed the CGR1 expression. The growth of the mutants could be partially overcome by thiol compounds such as GSH, dithiothreitol, cysteine, N-acetylcysteine and GSSG. Interestingly, C. albicans with CGR1 overexpressed showed defective hyphal growth on solid medium and attenuated virulence. We have also cloned the GCS1 gene encoding ${\gamma}$-glutamylcysteine synthetase which catalyzes the first step of glutathione biosynthesis. The gcs1/gcs1 mutants were nonviable in minimal defined medium. The growth of the mutants could be resumed by supplementing with GSH, GSSG and ${\gamma}$-glutamylcysteine in the medium. The mutants had increased intracellular D-erythroascorbic acid level up to 2.25-fold when transferred to GSH-free medium. When the mutants were depleted of GSH, they showed typical markers of apoptosis. In conclusion, these results suggest that glutathione is an essential metabolite, and involved in hyphal growth, virulence and apoptosis in C. albicans.

• BMB Reports
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• 제31권3호
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• pp.254-257
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• 1998

The gshI gene from the Escherichia coli K-12 strain codes for ${\gamma}-glutamylcysteine$ synthetase which mediates the rate-limiting step of glutathione biosynthesis. The isolated gshI gene from E. coli K-12 has an unusual translation initiation codon, UUG. The 494th amino acid is Ala rather than Gly which was found in a mutant strain E. coli B. In order to improve the translational rate of the gshI gene of E. coli K-12, the initiation codon, UUG, was changed to the usual AUG codon by the site-specific mutagenesis. This change has resulted in a 53% increase of ${\gamma}-glutamylcysteine$ synthetase activity. The enzyme activity was also improved by replacing $Ala^{494}$ with Val (A494V) or Leu (A494L). The replacement of $Ser^{495}$ with Thr (S495T) also resulted in a 62% increase of the enzyme activity. Therefore, the specific activity of ${\gamma}-glutamylcysteine$ synthetase was increased with the increasing chain length of the aliphathic amino acid at the site of the 494th amino acid (Ala<$Val{\leq}Leu$).

• 한국결정학회지
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• 제4권2호
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• pp.100-104
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• 1993

환원된 글루타치온은 모든 세포의 대사에 중요한 역할을 하고 있다. 글루타치온은 두개의 연속적인 반응으로 합성된 세개의 펩타이드로 구성되어 있다. 첫 번째 반응에서의 촉매효소가 GSH-I 이며, 두번째 반응에서의 촉매효소가 GSH-반이다. 대장균주의 글루 타치온 합성 기작은 주로 GSH-I의 되돌림 제어에 의 해 조절되고 있다. 이러한 생화학적 작용과 구조와의 관계를 알기 위한 첫 단계로 증기 확산 방을 방법과 모세관 확산 방법으로 실온에서 결정을 얻게 되었다. GSH-I 효소의 결정은 침전제 ammonium sulfate을 사용하여 얻었으며, 증기 확산 방을 방법으로는 10 일의 기간으로 실온에서 0.2 m x 0.2 mm x 0.2 mm 크기로 자랐으며. 이 결정은 싱크로트론 X-T3y 를 사용하여 약 4.0 A 까지 회절 시켰다. 또, 모세관 을 이용한 방법으로 얻은 결정은 40일의 기간으로 실온에서 0.25 mm X 0.25 mm X 0.3 mm 의 크기로 자랐으며, 이 결정은 회전 음극선의 X-ray를 사용하여 약 4.0 A까지 회절시켰다.

• 생명과학회지
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• 제14권1호
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• pp.141-147
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• 2004

가자 추출물을 흰쥐에 일정량 투여한 후 간장에 미치는 영향을 관찰할 목적으로 여러 가지 효소량의 변동을 검토하였다. 간 손상의 지표로 사용되는 AST, ALT활성을 측정한 결과 AST, ALT모두에서 정상군보다 300 mg/kg의 용량으로 2주 시료 투여한 군의 함량이 2배 이상 증가되는 것으로 나타났다. 가자 추출물이 지질과산화물 생성에 미치는 효과를 관찰한 결과, 300 mg/kg의 용량으로 2주 시료 투여한 군함량이 정상군에 비해 135.43%, 173.9% 정도 증가하는 결과를 나타내었다. 간 조직의 지질과산화물 반응에 관여하는 것으로 알려진 XO, AO, AD 및 AH활성에 대한 효과를 관찰한 결과 마이크로솜 분획에 존재하는 AD, AH의 활성은 저해 효과가 없었고, 세포질 효소인 XO, AO의 활성은 300 mg/kg의 용량으로 2주 시료 투여한 군 함량이 정상군에 비해 약 2배 증가됨을 볼 수 있었다. 가자 추출물에 의한 간 조직중 glutathione농도에 미치는 영향에 대해 관찰한 결과 2주 동안 300 mg/kg의 용량으로 투여한 군의 glutathione농도는 정상군에 비해 약 75% 감소하는 것으로 나타났다 가자 추출물 투여 후 glutathione의 함량 감소를 경감시키는 기전을 알아볼 목적으로 glutathione 합성에 관여하는 $\gamma$-GCS의 활성과 산화형 glutathione을 환원형 glutathione으로 환원시키는 GR의 활성을 관찰한 결과 정상군에 비해 GR이 56.6%, $\gamma$-GCS가 6.7% 정도 감소하는 것으로 나타났다. 이러한 glutathione의 함량 변동은 산화형 glutathione을 환원형 glutathione으로 환원시키는 GR의 활성에 영향을 주어 나타나는 결과로 생각된다. 가자 추출물이 지질과산화의 해독계에 미치는 영향을 관찰할 목적으로 catalase, GP 및 SOD의 활성을 측정한 결과 catalase, GP의 활성은 각각 77.5%, 64.3% 감소하는 결과를 나타냈으며, SOD의 활성은 정상군에 비해 약 3배 증가하는 것으로 나타났다.

• 생명과학회지
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• 제12권4호
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• pp.442-451
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• 2002

브롬(Br-)이온을 포함하는 지표수 또는 해수를 상수원 또는 어류양식용 물로 사용할 경우 소독, 살균을 위하여 오존(O$_3$)을 많이 사용한다. 이때 물속에 포함되어 있는 브름(Br-) 이온과 오존과의 반응에 의하여 독성물질인 Bromate(BrO$_3$-)가 산화 부산물로서 생성된다. 이 bromate의 생성반응에 대한 용액의 pH와 반응온도의 영향 및 bromate를 음용수중에 함유시키고 실험동물에 섭취시켰을 때의 생체독성에 미치는 기전을 관찰하였다. Bromate의 생성은 반응온도가 증가할수록 증가되지만, 낮은온도(15$^{\circ}C$)에서는 용액의 초기 pH가 3 인 경우는 초기 pH가 7, 10 인 용액의 경우보다 훨씬 적은 생성량을 나타내었다. Bromate를 음료수중에 0, 0.1, 0.2, 0.4g/L로하여 4, 12, 16, 20, 24주 투여하고서 신조직중의 지질과산화의 함량이 증가되었으며, 혈중 뇨소질소의 활성 및 뇨중 ${\gamma}$-glutamy-ltransferase의 활성은 대조군에 비하여 bromate의 투여로 현저히 증가되었으며, 뇨중 lactate dehydrogenase의 활성에는 별다른 영향이 없었다. Bromate의 투여로 xanthine oxidase 및 aldehyde oxidase의 활성은 bromate의 투여로 현저히 증가되었으며 glutathione의 농도 및 glutathione S-transferase의 활성도 대조군 보다 현저히 억제되었다. Glutathione의 생성계에 미치는 ${\gamma}$-giutarnylcystein synthetase의 활성은 대조군에 비해 bromate의 투여로 억제되었으며 glutathione redurtase의 활성은 별다른 영향이 없었다.

• 약학회지
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• 제53권6호
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• pp.314-320
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• 2009

We examined metabolic conversion of cysteine into glutathione (GSH) and taurine in rat liver under oxidative stress. Administration of tert-butylhydroperoxide (t-BHP) into the portal vein of male rats resulted in a rapid elevation of serum sorbitol dehydrogenase, alanine aminotransferase, and aspartate aminotransferase activities, which decreased gradually in 24 hr. Hepatic cysteine concentration was reduced in 3 hr, and recovered progressively, reaching a level greater than 200% of the normal value in 24 hr. GSH was increased both in liver and blood at 9 hr after t-BHP challenge, whereas hypotaurine or taurine was not altered. $\gamma$-Glutamylcysteine synthetase (GCS) activity was increased from 9 hr after t-BHP treatment, but protein expression of the GCS-heavy subunit was not changed in liver. Activity or expression of cysteine dioxygenase was not affected by t-BHP treatment. Taken together, these data show that an acute oxidant challenge to the rats may induce upregulation of cysteine availability and GCS activity, resulting in an enhancement of hepatic GSH synthesis, but the increased cysteine level does not stimulate taurine synthesis via cysteine sulfinate pathway. It is indicated that the regulation of GSH and taurine biosynthesis from cysteine is not solely dependent on the cysteine concentration in rat liver under oxidative stress.

• BMB Reports
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• 제33권6호
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• pp.514-518
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• 2000

Two open reading frames of Haemophilus influenzae, HI0572 and HI0751, showing homology to a yeast thioredoxin peroxidase II (TPx II) and an E. coli thiol peroxidase $P_{20}$, respectively, were cloned and expressed in E. coli, and then the proteins were subsequently purified and characterized. HI0751 protein showed the thioredoxin (Trx)-dependent peroxidase activity, whereas HI0572 protein showed glutathione-dependent peroxidase. The HI0572 is the first peroxiredoxin with glutathione peroxidase activity rather than thioredoxin peroxidase. Purified HI0572 and HI0751 proteins protected specifically the inactivation of glutamine synthetase by metal catalyzed oxidation (MCO) systems composed of $Fe^{3+}$, $O_2$ and mercaptans such as dithiothreitol, ${\beta}-mercaptoethanol$ and glutathione (GSH). Unlike the HI0751 protein, the HI0572 protein was more effective in protecting glutamine synthetase from inactivation by the $GSH/Fe^{3+}/O_2$ system. It seems that these unique properties of the HI0572 protein are due to the structure containing a glutaredoxin domain at it's C-terminal in addition to a peroxiredoxin domain.

• Biomolecules & Therapeutics
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• 제25권4호
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• pp.427-433
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• 2017

Previously, we demonstrated that galangin (3,5,7-trihydroxyflavone) protects human keratinocytes against ultraviolet B (UVB)-induced oxidative damage. In this study, we investigated the effect of galangin on induction of antioxidant enzymes involved in synthesis of reduced glutathione (GSH), and investigated the associated upstream signaling cascades. By activating nuclear factor-erythroid 2-related factor (Nrf2), galangin treatment significantly increased expression of glutamate-cysteine ligase catalytic subunit (GCLC) and glutathione synthetase (GSS). This activation of Nrf2 depended on extracellular signal-regulated kinases (ERKs) and protein kinase B (AKT) signaling. Inhibition of GSH in galangin-treated cells attenuated the protective effect of galangin against the deleterious effects of UVB. Our results reveal that galangin protects human keratinocytes by activating ERK/AKT-Nrf2, leading to elevated expression of GSH-synthesizing enzymes.