摄入异烟肼对家蚕幼虫体内谷胱甘肽氧化还原循环和谷胱甘肽S-转移酶活性的影响

为了建立家蚕Bombyx mori的药物筛选和毒性评价模型, 以剂量为2 000 mg/kg的抗结核模药异烟肼饲喂家蚕5龄第3天幼虫后检测其中肠和脂肪体的抗氧化解毒相关代谢的变化。结果表明： 雌蚕中肠组织中, 总谷胱甘肽(GSH+2GSSG)、 还原型谷胱甘肽(reduced glutathione, GSH)和氧化型谷胱甘肽(oxidized glutathione, GSSG)含量均呈现迅速上升再缓慢下降趋势; 谷胱甘肽S 转移酶(glutathione S-transferase, GST)活性升高到较大值后逐渐降低; GSH/GSSG的比值下降表明, 在72 min后中肠组织向氧化态转移。脂肪体组织中, 总谷胱甘肽、 GSH和GSSG含量变化均呈现迅速下降再迅速上升的趋势; GST活性达到最大值后逐渐降低后趋于平稳; GSH/GSSG比值升高表明, 在72 min后脂肪体组织向还原态转移。无论雌蚕还是雄蚕, 总谷胱甘肽、 GSH和GSSG含量以及GST活性均是脂肪体高于中肠。雌蚕的总谷胱甘肽含量、 GSH和GSSG含量高于雄蚕, 但雄蚕的GST活性高于雌性。结果说明, 摄入异烟肼引起了家蚕幼虫体内谷胱甘肽氧化还原状态的改变和酶活性的变化, 在这个过程中脂肪体起主要解毒代谢作用。     

植物谷胱甘肽还原酶的生物学特性及功能

谷胱甘肽还原酶(glutathione reductase,GR: EC 1.6.4.2)是植物体内一种重要的抗氧化酶类,其主要的生理功能是将氧化型谷胱甘肽(oxidaized glutathione disulfide,GSSG)还原成还原型谷胱甘肽(reduced glutathione,GSH),从而为活性氧（reactive oxygen species,ROS）的清除提供还原力,保护植物免受伤害.文中主要从Gr基因及其氨基酸序列的比较等方面分析了该酶的生物学特性;又对植物逆境响应,酶基因的缺失等方面的研究进行综述,阐释了GR酶在植物体内的作用原理、在逆境胁迫中抗逆表达调控途径及其作用机制;并对已有的研究成果进行总结分析,探讨了GR酶可能的起源及系统进化过程,为今后该酶的研究提供理论参考.     

谷胱甘肽与四氧嘧啶糖尿病

一、谷胱甘肽和四氧嘧啶的特性谷胱甘肽(glutathione)(C_(10)H_(17)N_3O_6S)是由谷氨酸、半胱氨酸、甘氨酸构成的三肽(tripeptide),简称GSH。谷胱甘肽纯结晶体在190°—192℃熔融而分解,在水溶液中的旋光度为[α]_D—97°,极易溶于水,不溶于有机溶剂,与铜能结合成不溶性化合物。它广泛地存在于人体的若干肌肉组织、肝、各种腺体内,也存在于某些植物组织内。人体血球内含有GSH,但血清内不含有”。有人假定人体的胰脏平均重85克,其重量的0.5%是胰岛组织(约重425毫克),如不计其中不同类型的细胞,而假定胰岛内GSH含量等于整个胰脏中的含量(60毫     

谷胱甘肽/谷胱甘肽过氧化物酶系统在微生物细胞抗氧胁迫系统中的作用

谷胱甘肽(GSH)/谷胱甘肽过氧化物酶(GPx)系统在不同微生物细胞抵抗氧胁迫中的生理功能不尽相同。该系统在真核模式微生物酿酒酵母中是必需存在的,在维持胞内氧化还原平衡和抵抗氧胁迫中发挥主要作用。然而,在原核微生物中,该系统只是条件性的,即部分胞内存在谷胱甘肽还原酶和GPx的原核微生物,如流感嗜血杆菌和乳酸乳球菌,可通过从胞外吸收GSH,形成条件性的依赖于GSH的GPx系统,参与抵抗氧胁迫。     

谷胱甘肽/谷胱甘肽过氧化物酶系统在微生物细胞抗氧胁迫系统中的作用

谷胱甘肽(GSH)/谷胱甘肽过氧化物酶(GPx)系统在不同微生物细胞抵抗氧胁迫中的生理功能不尽相同。该系统在真核模式微生物酿酒酵母中是必需存在的,在维持胞内氧化还原平衡和抵抗氧胁迫中发挥主要作用。然而,在原核微生物中,该系统只是条件性的,即部分胞内存在谷胱甘肽还原酶和GPx的原核微生物,如流感嗜血杆菌和乳酸乳球菌,可通过从胞外吸收GSH,形成条件性的依赖于GSH的GPx系统,参与抵抗氧胁迫。     

谷胱甘肽促进液体发酵体系中蛹虫草合成虫草素

虫草素是药用真菌蛹虫草Cordyceps militaris的主要活性成分,具有抗癌、抗肿瘤、抗病毒等多种生理活性.研究表明,氧化应激参与丝状真菌的次级代谢调控,然而在蛹虫草虫草素代谢中尚未见报道.本研究以蛹虫草深层液体发酵体系为研究对象,添加谷胱甘肽(glutathione,GSH)调节细胞氧化还原状态,考察其对虫草...     

甲胺磷农药对小白菜中几种抗氧化物的影响

以小白菜为研究对象,喷洒一定浓度甲胺磷农药后,测定7d内小白菜体内可溶性蛋白质的含量及各种抗氧化物如超氧化物歧化酶（superoxide dismutase,SOD）、谷胱甘肽（glutathione,GSH）、谷胱甘肽-S-转移酶（glutathione-S-transferase,GST）、过氧化氢酶（catalase,CAT）、谷胱甘肽过氧化物酶（glutathione peroxidase,GPX）等活性的变化。结果表明,喷药后第1天各种物质含量相对与对照变化不大,第2～6天小白菜中蛋白质、GSH、SOD、CAT都高于对照,而GPX、GST的含量低于对照,第7天都又还原到与对照接近。说明有机磷农药喷洒后植物体内产生了氧自由基,进而诱导细咆内防御活性氧自由基毒害的物质产生,5～6天后机体恢复正常。实验为食品卫生检验提供了一个参考标准。     

谷胱甘肽在肝脏疾病相关信号通路中的作用及研究进展

谷胱甘肽(GSH)是细胞内主要的抗氧剂和氧化还原、细胞信号调节器,它能还原过氧化氢、清除活性氧(ROS)和含氮自由基使细胞免受氧化应激损伤。不管细胞内是否存在ROS氧化细胞蛋白,谷胱甘肽均能诱导氧化还原反应发生转变,进一步使信号传导功能及转录因子分子功能发生改变。大量实验表明,ROS和GSH在多条细胞信号调节通路中发挥着重要作用。主要阐述了Fas、TNF-α和NF-κB信号通路及线粒体凋亡途径及GSH在这些通路中的作用。尤其是线粒体GSH耗竭能诱导线粒体内ROS显著增加,从而损害细胞生物能量和诱导线粒体通透性转换孔开启。根据线粒体损害程度,NF-κB信号通路可被抑制,肝细胞也可能经历不同的死亡模式(凋亡或坏死)并对刺激细胞死亡信号(如TNF-α)也更敏感。这些过程涉及许多肝脏疾病的发病机理。     

即时浸酸显著降低滞育家蚕卵的还原型与氧化型谷胱甘肽比值

即时浸酸在阻止家蚕Bombyx mori卵滞育发动的同时, 显著提高了家蚕卵H₂O₂含量。还原型谷胱甘肽（reduced glutathione, GSH）与氧化型谷胱甘肽（oxidized glutathione, GSSG）的比值是一种氧化胁迫状态的动态指标。为了调查即时浸酸是否造成滞育家蚕卵氧化胁迫, 本研究利用分光光度法分别测定了滞育家蚕卵和5 min即时浸酸滞育家蚕卵中GSH和GSSG含量以及谷胱甘肽转移酶（glutathione-S-transferase, GST）活性。结果表明: 处理后24 h, 即时浸酸处理家蚕卵的总谷胱甘肽（GSH+2GSSG）含量、 GSH含量、 GSSG含量、 GSH/GSSG比值和GST活性分别相当于同期滞育家蚕卵的204%, 78%, 550%, 14%和97%。据此推测, 即时浸酸在阻止滞育发动的同时, 可能通过促进GSH氧化为GSSG, 而显著降低了GSH/GSSG比值, 使家蚕卵处于过氧化状态。     

双依他尼酸乙醇胺对谷胱甘肽S-转硫酶mu的选择性抑制作用

谷胱甘肽S-转移酶(GST)的同工酶mu(GSTM)高表达与卵巢癌顺铂耐药有关.以GST非选择性抑制剂依他尼酸设计二价潜抑制剂双依他尼酸乙醇胺(aminoethanol di-ethacrynic acid,ADEA),测定ADEA及其与还原型谷胱甘肽(glutathione,GSH)加合物对GST同工酶亚型A1、P1...     

Glutathione regulates the expression of gamma-glutamylcysteine synthetase via the Met4 transcription factor

Our previous studies have shown that glutathione is an essential metabolite in the yeast Saccharomyces cerevisiae because a mutant deleted for GSH1, encoding the first enzyme in gamma-l-glutamyl-l-cysteinylglycine (GSH) biosynthesis, cannot grow in its absence. In contrast, strains deleted for GSH2, encoding the second step in GSH synthesis, grow poorly as the dipeptide intermediate, gamma-glutamylcysteine, can partially substitute for GSH. In this present study, we identify two high copy suppressors that rescue the poor growth of the gsh2 mutant in the absence of GSH. The first contains GSH1, indicating that gamma-glutamylcysteine can functionally replace GSH if it is present in sufficiently high quantities. The second contains CDC34, encoding a ubiquitin conjugating enzyme, indicating a link between the ubiquitin and GSH stress protective systems. We show that CDC34 rescues the growth of the gsh2 mutant by inducing the Met4-dependent expression of GSH1 and elevating the cellular levels of gamma-glutamylcysteine. Furthermore, this mechanism normally operates to regulate GSH biosynthesis in the cell, as GSH1 promoter activity is induced in a Met4-dependent manner in a gsh1 mutant which is devoid of GSH, and the addition of exogenous GSH represses GSH1 expression. Analysis of a cis2 mutant, which cannot breakdown GSH, confirmed that GSH and not a metabolic product, serves as the regulatory molecule. However, this is not a general mechanism affecting all Met4-regulated genes, as MET16 expression is unaffected in a gsh1 mutant, and GSH acts as a poor repressor of MET16 expression compared with methionine. In summary, GSH biosynthesis is regulated in parallel with sulphate assimilation by activity of the Met4 protein, but GSH1-specific mechanisms exist that respond to GSH availability.     

Interrelationship between anionic and cationic forms of glutathione S-transferases of human liver.

Human liver glutathione S-transferases (GSH S-transferases) were fractionated into cationic and anionic proteins. During fractionation with (NH4)2SO4 the anionic GSH S-transferases are concentrated in the 65%-saturated-(NH4)2SO4 fraction, whereas the cationic GSH S-transferases separate in the 80%-saturated-(NH4)2SO4 fraction. From the 65%-saturated-(NH4)2SO4 fraction two new anionic GSH S-transferases, omega and psi, were purified to homogeneity by using ion-exchange chromatography on DEAE-cellulose, Sephadex G-200 gel filtration, affinity chromatography on GSH bound to epoxy-activated Sepharose and isoelectric focusing. By a similar procedure, cationic GSH S-transferases were purified from the 80%-saturated-(NH4)2SO4 fraction. Isoelectric points of GSH S-transferases omega and psi are 4.6 and 5.4 respectively. GSH S-transferase omega is the major anionic GSH S-transferase of human liver, whereas GSH S-transferase psi is present only in traces. The subunit mol.wt. of GSH S-transferase omega is about 22500, whereas that of cationic GSH S-transferases is about 24500. Kinetic and structural properties as well as the amino acid composition of GSH S-transferase omega are described. The antibodies raised against cationic GSH S-transferases cross-react with GSH S-transferase omega. There are significant differences between the catalytic properties of GSH S-transferase omega and the cationic GSH S-transferases. GSH peroxidase II activity is displayed by all five cationic GSH S-transferases, whereas both anionic GSH S-transferases do not display this activity.     

Astrocytes Protect Against Copper-Catalysed Loss of Extracellular Glutathione

Glutathione (GSH) is one of the major antioxidants in the brain. GSH is secreted by astrocytes and this extracellular GSH is used by neurones to maintain and increase their intracellular GSH levels. For efficient GSH trafficking between astrocytes and neurones, GSH needs to be maintained in the reduced form. In model systems, GSH trafficking has been shown to be essential for neuroprotection against a variety of stress conditions. Previously we and others have shown that GSH and thiols are unstable in cell culture media and are easily oxidised. In the present study it is shown that nanomolar concentrations of copper (II) ions can cause decay of GSH in cell culture media. Increased free or redox active copper has been implicated in a variety of diseases and degradation of extracellular GSH is a possible mechanism by which it exerts its harmful effects. Rat astrocytes, a human astrocytoma cell line and astrocyte-conditioned media, in the absence of cells, are able to retard this copper-catalysed decay of GSH and maintain GSH in its reduced form. The protective effect of astrocytes appears to be a combination of copper removing and antioxidant mechanisms. The importance of these protective mechanisms is discussed with regards to neurodegenerative diseases.     

Root uptake, transport, and metabolism of externally applied glutathione in Phaseolus vulgaris seedlings

The most abundant thiol in beans (Phaseolus vulgaris L. cv. Saxa) is the tripeptide homoglutathione (hGSH) rather than glutathione (GSH). At the whole-plant level the GSH content is less than 0.5% of the hGSH content. In the present study GSH was supplied to the roots of bean seedlings to test whether GSH can be taken up by roots and transported to the shoot. Therefore, 12-day-old plants were exposed to 1 mmol/L GSH for 4, 8 and 24 h prior to harvest. In response to this GSH exposure, elevated GSH contents were found in all tissues. After 4 h the GSH content increased in the roots from 1 +/- 1 to 22 +/- 2 nmol GSH g(-1) fresh weight (FW), in the leaves from 2 +/- 1 to 9 +/- 4 nmol GSH g(-1) FW, and in the apex from 30 +/- 5 to 75 +/- 4 nmol GSH g(-1) FW. These data indicate that GSH is taken up by bean roots and is transported to above above-ground parts of the plants. Roots exposed to GSH for 24 h contained 2-fold higher cysteine (Cys) and hGSH contents than the controls. Apparently, GSH taken up by the roots is not only loaded into the xylem but also partially degraded and used for hGSH synthesis.     

Level of glutathione is regulated by ATP-dependent ligation of glutamate and cysteine through photosynthesis in Arabidopsis thaliana: mechanism of strong interaction of light intensity with flowering

Glutathione (GSH) is associated with flowering in Arabidopsis thaliana, but how GSH biosynthesis is regulated to control the transition to flowering remains to be elucidated. Since the key reaction of GSH synthesis is catalyzed by gamma-glutamylcysteine synthetase (gamma-ECS) and all the gamma-ECS cDNAs examined contained extra sequences for plastid targeting, we investigated the relationships among GSH levels, photosynthesis and flowering. The GSH level in Arabidopsis increased with the light intensity. The ch1 mutants defective in a light-harvesting antenna in photosystem II showed reduced GSH levels with accumulation of the GSH precursor cysteine, and introduction of the gamma-ECS gene GSH1 under the control of the cauliflower mosaic virus 35S promoter (35S-GSH1) into the ch1 mutant altered the GSH level in response to the gamma-ECS mRNA level. These indicate that photosynthesis limits the gamma-ECS reaction to regulate GSH biosynthesis. Like the glutathione-biosynthesis-defective cad2-1 mutant, the ch1 mutants flowered late under weak-light conditions, and this late-flowering phenotype was rescued by supplementation of GSH. Introduction of the 35S-GSH1 construct into the ch1 mutant altered flowering in response to the gamma-ECS mRNA and GSH levels. These findings indicate that flowering in A. thaliana is regulated by the gamma-ECS reaction of GSH synthesis that is coupled with photosynthesis.     

Glutathione pathways in the brain

The antioxidant glutathione (GSH) is essential for the cellular detoxification of reactive oxygen species in brain cells. A compromised GSH system in the brain has been connected with the oxidative stress occuring in neurological diseases. Recent data demonstrate that besides intracellular functions GSH has also important extracellular functions in brain. In this respect astrocytes appear to play a key role in the GSH metabolism of the brain, since astroglial GSH export is essential for providing GSH precursors to neurons. Of the different brain cell types studied in vitro only astrocytes release substantial amounts of GSH. In addition, during oxidative stress astrocytes efficiently export glutathione disulfide (GSSG). The multidrug resistance protein 1 participates in both the export of GSH and GSSG from astrocytes. This review focuses on recent results on the export of GSH and GSSG from brain cells as well as on the functions of extracellular GSH in the brain. In addition, implications of disturbed GSH pathways in brain for neurodegenerative diseases will be discussed.     

Role of reduced glutathione efflux in apoptosis of immortalized human keratinocytes induced by UVA

We have investigated the role played by GSH efflux in apoptosis of human HaCaT keratinocytes induced by UVA irradiation. UVA irradiation of HaCaT cells caused a rapid rise in GSH efflux across the intact cell membrane, followed by an increase in apoptosis. GSH efflux was stimulated by glucose and was reduced by the addition of exogenous GSH and intracellular GSH depletion by buthionine sulfoximine, suggesting that GSH transport is active and is influenced by the GSH concentration gradient across the cell membrane. Verapamil and cyclosporin A, blockers of the multidrug resistance-associated protein, decreased UVA-induced GSH efflux. GSH efflux occurred within 2 h of UVA irradiation, suggesting that the stimulation of GSH efflux is due to an increase in the activity of pre-existing multidrug resistance-associated protein transporter carrier. Although inhibition of GSH efflux did not affect caspase activation and DNA fragmentation, it delayed the gradual increase in plasma membrane permeability and reduced phosphatidylserine translocation in HaCaT cells. It is therefore likely that upon UVA irradiation, GSH efflux increased the intracellular oxidative stress without intervention of reactive oxygen species, thus resulting in more phosphatidylserine externalization and membrane rearrangement. These provide targets for macrophage recognition and phagocytosis and thus minimize the potential to invoke inflammation or neoplastic transformation.