排序方式: 共有173条查询结果,搜索用时 31 毫秒
51.
Abramczyk O Tavares CD Devkota AK Ryazanov AG Turk BE Riggs AF Ozpolat B Dalby KN 《Protein expression and purification》2011,79(2):237-244
The eukaryotic elongation factor 2 kinase (eEF-2K) modulates the rate of protein synthesis by impeding the elongation phase of translation by inactivating the eukaryotic elongation factor 2 (eEF-2) via phosphorylation. eEF-2K is known to be activated by calcium and calmodulin, whereas the mTOR and MAPK pathways are suggested to negatively regulate kinase activity. Despite its pivotal role in translation regulation and potential role in tumor survival, the structure, function, and regulation of eEF-2K have not been described in detail. This deficiency may result from the difficulty of obtaining the recombinant kinase in a form suitable for biochemical analysis. Here we report the purification and characterization of recombinant human eEF-2K expressed in the Escherichia coli strain Rosetta-gami 2(DE3). Successive chromatography steps utilizing Ni-NTA affinity, anion-exchange, and gel filtration columns accomplished purification. Cleavage of the thioredoxin-His(6)-tag from the N-terminus of the expressed kinase with TEV protease yielded 9 mg of recombinant (G-D-I)-eEF-2K per liter of culture. Light scattering shows that eEF-2K is a monomer of ~85 kDa. In vitro kinetic analysis confirmed that recombinant human eEF-2K is able to phosphorylate wheat germ eEF-2 with kinetic parameters comparable to the mammalian enzyme. 相似文献
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Mehmet Kaya Nurcan Orhan Emrah Karabacak Metin Berkant Bahceci Nadir Arican Bulent Ahishali Gonul Kemikler Atilla Uslu Aydin Cevik Canan Ugur Yilmaz Mutlu Kucuk Candan Gürses 《Life sciences》2013,92(4-5):289-297
AimsThis study investigates the effects of vagus nerve stimulation (VNS) on seizure severity and blood–brain barrier (BBB) integrity in kindled rats with cortical dysplasia (CD).Main methodsPregnant rats were exposed to 145 cGy of gamma-irradiation on day 17 of pregnancy. In offsprings, kindling was induced by giving subconvulsive doses of pentylenetetrazole. Left VNS was performed for 48 h at output currents of 0.5 or 1 mA. Horseradish peroxidase (HRP) was used to study the BBB permeability. Immunohistochemistry for occludin and P-glycoprotein (P-gp) was also performed.Key findingsKindled rats with CD exhibited seizures with mean Racine's scores of 3.57 ± 1.2 during video EEG recording. Kindled animals with CD receiving VNS at 0.5 and 1.0 mA did not exhibit either clinical or electrophysiological signs of seizure. Immunostaining for occludin, a tight junction protein, in hippocampus remained relatively intact in all groups. VNS-treated and -untreated kindled animals with CD revealed intense immunostaining for P-gp in hippocampal formation (P < 0.01). Electron microscopic observations revealed frequent transport vesicles containing electron-dense HRP reaction products in the cytoplasm of brain capillary endothelial cells in both cerebral cortex and hippocampus of kindled animals with CD. Those which were exposed to 1 mA VNS were observed to have brain capillary endothelial cells largely devoid of HRP reaction products in both cerebral cortex and hippocampus.SignificanceThe results of this study suggest that VNS therapy at 1 mA inhibits seizure activity and protects BBB integrity by limiting the enhancement of transcellular pathway in kindled animals with CD. 相似文献
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Improved nitrogen nutrition enhances root uptake, root-to-shoot translocation and remobilization of zinc ((65) Zn) in wheat 总被引:4,自引:0,他引:4
This study focussed on the effect of increasing nitrogen (N) supply on root uptake and root-to-shoot translocation of zinc (Zn) as well as retranslocation of foliar-applied Zn in durum wheat (Triticum durum). Nutrient solution experiments were conducted to examine the root uptake and root-to-shoot translocation of (65) Zn in seedlings precultured with different N supplies. In additional experiments, the effect of varied N nutrition on retranslocation of foliar-applied (65) Zn was tested at both the vegetative and generative stages. When N supply was increased, the (65) Zn uptake by roots was enhanced by up to threefold and the (65) Zn translocation from roots to shoots increased by up to eightfold, while plant growth was affected to a much smaller degree. Retranslocation of (65) Zn from old into young leaves and from flag leaves to grains also showed marked positive responses to increasing N supply. The results demonstrate that the N-nutritional status of wheat affects major steps in the route of Zn from the growth medium to the grain, including its uptake, xylem transport and remobilization via phloem. Thus, N is a critical player in the uptake and accumulation of Zn in plants, which deserves special attention in biofortification of food crops with Zn. 相似文献
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Kiziler AR Aydemir B Onaran I Alici B Ozkara H Gulyasar T Akyolcu MC 《Biological trace element research》2007,120(1-3):82-91
We measured the levels of malondialdehyde (MDA), protein carbonyls, glutathione S-transferase (GST) and reducte glutathione (GSH) in seminal plasma and spermatozoa from 95 subjects including 50 infertile
patients to evaluate the association between oxidative stress and damage and the components of the anti-oxidant defenses in
seminal plasma and spermatozoa of infertile subjects and concentrations of cadmium (Cd) and lead (Pb) in the blood and seminal
plasma because of tobacco smoke exposure. The reactive oxygen species (ROS) in spermatozoa were also evaluated by luminol
(5-amino-2,3-dihydro-1,4-phthalazinedione)-enhanced chemiluminescence assay. The sperm count, motility, and morphology in
the smokers infertile group were found to be lower than those in the fertile male group and nonsmokers infertile group (p < 0.001). Concentrations of Cd, Pb, MDA, protein carbonyls, and ROS levels in the smokers infertile group were significantly
higher than those in the fertile male and nonsmokers infertile male groups (p < 0.001). However, GSH levels and GST activities were decreased in the smokers infertile male group than those in the fertile
male and nonsmokers infertile male groups (p < 0.001). The results indicate that smoking could affect semen quality and oxidative lipid and protein damage in human spermatozoa.
From Pearson correlation analysis, positive correlations were demonstrated between the seminal plasma Cd and seminal plasma
protein carbonyls and between seminal plasma Pb and spermatozoa ROS levels in smokers of the subfertile group, while there
was a significant positive correlation between blood Cd and ROS levels in smokers of the fertile group. There was also a significant
negative correlation of the Cd level of the blood and GSH levels of the sperm and seminal plasma. These findings suggest that
cigarette smoking enhances the levels of Cd and Pb in seminal plasma and blood and the extent of oxidative damage associated
with a decrease in components of the anti-oxidant defenses in the sperm of infertile males. 相似文献
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Coling DE Yu KC Somand D Satar B Bai U Huang TT Seidman MD Epstein CJ Mhatre AN Lalwani AK 《Free radical biology & medicine》2003,34(7):873-880
Reactive oxygen species (ROS) have been implicated in hearing loss associated with aging and noise exposure. Superoxide dismutases (SODs) form a first line of defense against damage mediated by the superoxide anion, the most common ROS. Absence of Cu/Zn SOD (SOD1) has been shown to potentiate hearing loss related to noise exposure and age. Conversely, overexpression of SOD1 may be hypothesized to afford a protection from age- and noise-related hearing loss. This hypothesis may be tested using a transgenic mouse model carrying the human SOD1 gene. Contrary to expectations, here, we report that no protection against age-related hearing loss was observed in mice up to 7 months of age or from noise-induced hearing loss when 8 week old mice were exposed to broadband noise (4-45 kHz, 110 dB for 1 h). Mitochondrial DNA deletion, an index of aging, was elevated in the acoustic nerve of transgenic mice compared to nontransgenic littermates. The results indicate the complexity of oxidative metabolism in the cochlea is greater than previously hypothesized. 相似文献
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Janet M. Turan Abigail H. Hatcher Jos�� Medema-Wijnveen Maricianah Onono Suellen Miller Elizabeth A. Bukusi Bulent Turan Craig R. Cohen 《PLoS medicine》2012,9(8)