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。     

植物谷胱甘肽过氧化物酶研究进展

氧化胁迫可诱导植物多种防御酶的产生,其中包括超氧化物歧化酶(SOD,EC1.15.L1)、抗坏血酸过氧化物酶(APX,EC1.11.1.11)、过氧化氢酶(CAT,E.C.1.11.1.6)和谷胱甘肽过氧化物酶(GPXs,EC1.11.1.9).它们在清除活性氧过程中起着不同的作用.GPXs是动物体内清除氧自由基的主要酶类,但它在植物中的功能报道甚少.最近几年研究表明,植物体内也存在类似于哺乳动物的GPXs家族,并对其功能研究已初见端倪.本文综述了有关GPXs的结构以及植物GPXs功能的研究进展.     

植物谷胱甘肽过氧化物酶研究进展

氧化胁迫可诱导植物多种防御酶的产生, 其中包括超氧化物歧化酶(SOD, EC1.15.1.1)、抗坏血酸过氧化物酶(APX, EC1.11.1.11)、过氧化氢酶(CAT, E.C.1.11.1.6 )和谷胱甘肽过氧化物酶(GPXs,EC1.11.1.9)。它们在清除活性氧过程中起着不同的作用。GPXs是动物体内清除氧自由基的主要酶类,但它在植物中的功能报道甚少。最近几年研究表明, 植物体内也存在类似于哺乳动物的GPXs家族, 并对其功能研究已初见端倪。本文综述了有关GPXs的结构以及植物GPXs功能的研究进展。     

硒,谷胱甘肽过氧化物酶和不饱和脂肪酸在鼠亚细胞中的分布

采和梯度离心和放射性同位素等方法从鼠脑中分离得到髓磷脂、突触囊、轻突触体、重突触体、线粒体６个亚细胞组分,分别测定了各亚细胞中硒－７５、谷胱甘肽过氧化物酶和不饱和脂肪酸的含量,结果表明这上结成分在鼠脑亚细胞中的分布呈明显的相关性,同时首次在突触囊、线粒体和微粒体中检测到三咱不同的谷胱甘肽过氧化物酶的活性峰,其中之一可能是红细胞谷胱甘过氧化物酶（ＥＣ１．１１．１．９）。还就机体的自我保护机制和硒在脑     

硒、谷胱甘肽过氧化物酶和不饱和脂肪酸在鼠脑亚细胞中的分布

采用梯度离心和放射性同位素等方法从鼠脑中分离得到髓磷脂、突触囊、轻突触体、重突触体、线粒体６个亚细胞组分。分别测定了各亚细胞中硒－７５、谷胱甘肽过氧化物酶和不饱和脂肪酸的含量,结果表明这些成分在鼠脑亚细胞中的分布呈现明显的相关性,同时首次在突触囊、线粒体和微粒体中检测到三种不同的谷胱甘肽过氧化物酶的活性峰,其中之一可能是红细胞谷胱甘肽过氧化物酶（ＥＣ１．１１．１．９）．还就机体的自我保护机制和硒在脑组织中的重要作用进行了讨论。     

纳米硒对肉鸡肝细胞中细胞谷胱甘肽过氧化物酶活性的影响

以亚硒酸钠和蛋氨酸硒为对照,研究了纳米单质硒(纳米硒)对肉鸡肝细胞中细胞谷胱甘肽过氧化物酶(cGPx)活性的影响。每种硒源分别以0.01、0.05、0.10、0.30、0.50、1.0μmol/L6个硒添加浓度培养肉鸡肝细胞,测定培养后0、24、48、72、96h肉鸡肝细胞cGPx活性。结果显示:亚硒酸钠添加浓度(以硒计)在0.01￣0.10μmol/L、蛋氨酸硒和纳米硒添加浓度(以硒计)在0.01￣0.30μmol/L,cGPx活性随着硒添加浓度的增加而增加;亚硒酸钠添加浓度在0.10￣1.0μmol/L、蛋氨酸硒添加浓度在0.30￣1.0μmol/L,cGPx活性随着硒添加浓度的增加而下降,而纳米硒添加浓度在0.30￣1.0μmol/L,cGPx活性始终保持在高峰平台。结果表明,3种硒源的剂量-效应关系曲线中的最适剂量范围宽度依次为:纳米硒>蛋氨酸硒>亚硒酸钠。     

谷胱甘肽磷脂氢过氧化物酶研究进展

谷胱甘肽磷脂氢过氧化物酶(PHGPx)是生物体内一种重要的抗氧化酶。它是一种硒依赖性蛋白,在谷胱甘肽(GSH)的参与下能特异性地还原磷脂氢过氧化物(PLOOH)和胆固醇氢过氧化物(ChOOH),从而保护生物膜免受过氧化损伤。它还是核酸等生物大分子的重要保护剂,并且在细胞凋亡调控中发挥作用。     

高温胁迫对扶桑绵粉蚧成虫过氧化物酶和谷胱甘肽-S-转移酶活性的影响

为了研究高温胁迫对扶桑绵粉蚧的影响,将该虫分别置于35℃、38℃、41℃、44℃和47℃水浴处理2 h、3 h和4 h,然后置于26℃下恢复2 h,测定成虫的过氧化物酶(POD)和谷胱甘肽-S-转移酶(GSTs)活力的变化。结果表明在处理2 h、3 h和4 h下,对照(26℃)的POD活力值分别为(0.0527±0.0015)mmol/min、(0.0508±0.0015)mmol/min和(0.0483±0.0072)mmol/min,均高于高温各处理的POD活力值;5个温度处理下的POD活力值变化为低(35℃)-高(38℃)-低(41、44、47℃)的变化趋势;当处理2 h时,不同温度下的POD活力值分别是(0.0183±0.0009)(35℃)、(0.0480±0.0012)(38℃)、(0.0227±0.0012)(41℃)、(0.0197±0.0003)(44℃)、(0.0173±0.0007)(47℃)mmol/min。且在不同温度和时间处理下,成虫的GSTs活性变化趋势与POD活性变化趋势一致。即不同时间处理下,对照的GSTs活性均高于高温各处理的GSTs,其对照的GSTs活力值分别为(0.5537±0.0044)(2 h)、(0.5358±0.0078)(3 h)和(0.5291±0.0264)(4 h)mmol/min;5个温度处理下的GSTs活力值变化为低(35℃)-高(38℃)-低(41℃、44℃、47℃)的变化趋势;当处理3 h时,不同温度下的GSTs活力值分别是(0.5114±0.0116)(35℃)、(0.5426±0.0009)(38℃)、(0.4861±0.0073)(41℃)、(0.3657±0.0029)(44℃)、(0.3404±0.0156)mmol/min(47℃)。因此高温对扶桑绵粉蚧体内的POD和GSTs活力存在影响。     

丹参谷胱甘肽过氧化物酶的生物信息学分析

谷胱甘肽过氧化物酶(glutathione peroxidase,GPX)是动植物体内一种重要的抗氧化酶,它能够清除机体逆境胁迫而产生的过氧化氢和脂质过氧化物,使机体进行正常生长发育,因此解析丹参GPX的氨基酸序列,并与其它植物进行比较,为丹参GPX基因的后续研究提供重要参考.采用生物信息学的方法,在丹参基因组库中找到...     

Cytoprotection against lipid hydroperoxides correlates with increased glutathione peroxidase activities, but not selenium uptake from different selenocompounds

Cells cultivated under standard conditions were highly deficient in tocopherol, selenium, and glutathione peroxidase (GPx) activities. We investigated whether and to what extent the addition of different selenocompounds to growth media would alter biochemical, physiological, and pathophysiological parameters of cultured liver cells. Cellular uptake of selenium, GPx activities, and cytoprotection were measured and compared in human hepatoma cells (HepG2). Selenite and selenocystine were Se donors of high bioavailability (i.e., with these culture supplements, the increased Se uptake, induction of GPx isoenzymes, and protection of treated cells from lipid hydroperoxides were well correlated). In contrast, selenium from selenomethionine was incorporated into cellular proteins but had no effect on GPx activities or cytoprotection. The data show that not all selenium donors provide selenium, which is bioactivated to act as antioxidant. Thus, cellular selenium content, in general, did not correlate with cytoprotective activity of this trace element. However, cellular GPx activities at different times, with different concentrations, and with different Se donors always correlated with protection from lipid hydroperoxides and may, thus, represent a more reliable parameter to define adequate Se supply.     

Auxin autotrophic tobacco callus tissues resist oxidative stress: the importance of glutathione S-transferase and glutathione peroxidase activities in auxin heterotrophic and autotrophic calli

Auxin autotrophic and heterotrophic tobacco callus lines were grown on MS medium with or without 100 mmol/L NaCl and growth and some of the stress-related activities, such as GPX, SOD, CAT, GST, GSH-PX, as well as the concentration of ethylene and H2O2, were measured and compared with each other. The auxin autotrophic calli grew slower, however, on the NaCl-containing medium the growth rate was higher than that of the heterotrophic cultures after two weeks of culturing. The stress-related ethylene production was lower in the autotrophic cultures and, contrary to the heterotrophic tissues, its level did not change significantly upon NaCl treatment. The guaiacol peroxidase (GPX) activities were higher in the autotrophic tissues in all cell fractions regardless of the presence of NaCl. Treated with NaCl, the GPX activities elevated in the soluble and covalently-bound fractions in the heterotrophic calli, but were not further increased in the autotrophic line. SOD and CAT activities were higher in the heterotrophic tissues, and were increased further by 100 mmol/L NaCl treatment. The GST and GSH-PX activities were higher in the autotrophic line, which might explain their enhanced stress tolerance. In the autotrophic tissues, the elevated antioxidant activities led to reduced levels of H2O2 and malondialdehyde; under mild NaCl stress, these levels decreased further. The lower growth rate and the effective protection against NaCl stress-induced oxidative damage of the autotrophic line can be explained by the cell wall-bound peroxidase and GSH-PX activities in the auxin autotrophic tissues. Their maintained growth rate indicates that the autotropic cultures were more resistant to exogenous H2O2.     

Serum antioxidant enzyme activity in Parkinson's disease

Summary The activities of superoxide dismutase (SOD; EC 1.15.1.1) and glutathione peroxidase (GSHP_x; EC 1.11.1.9.), the enzymes that metabolize the superoxide anion and hydrogen peroxide, respectively, were measured in serum from healthy subjects and patients with Parkinson's disease (PD). The activities of SOD and GSHP_x in patients with PD were higher than those in normal healthy individuals. These results suggest that the increased activities of these enzymes could be due to oxidative stress in the initial stages of this disease.     

Ketogenic Diet Increases Glutathione Peroxidase Activity in Rat Hippocampus

Ketogenic diets have been used in the treatment of refractory childhood epilepsy for almost 80 years; however, we know little about the underlying biochemical basis of their action. In this study, we evaluate oxidative stress in different brain regions from Wistar rats fed a ketogenic diet. Cerebral cortex appears to have not been affected by this diet, and cerebellum presented a decrease in antioxidant capacity measured by a luminol oxidation assay without changes in antioxidant enzyme activities—glutathione peroxidase, catalase, and superoxide dismutase. In the hippocampus, however, we observed an increase in antioxidant activity accompanied by an increase of glutathione peroxidase (about 4 times) and no changes in lipoperoxidation levels. We suggest that the higher activity of this enzyme induced by ketogenic diet in hippocampus might contribute to protect this structure from neurodegenerative sequelae of convulsive disorders.