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排序方式: 共有803条查询结果,搜索用时 15 毫秒
1.
Complex formation of zinc and cadmium with glutathione 总被引:7,自引:0,他引:7
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Hemorrhage induces an increase in serum TNF which is not associated with elevated levels of endotoxin 总被引:12,自引:0,他引:12
Although tumor necrosis factor (TNF) and interleukin 6 (IL 6) are purported to be important mediators of inflammatory responses following trauma, it is not known if the serum levels of these cytokines are altered by simple hemorrhage. The objective of this study therefore was to determine whether or not: 1) there is any elevation of TNF or IL 6, and 2) if endotoxin, an important upregulator of these cytokines, is also increased following hemorrhage. To study this, C3H/HeN mice were bled to, and maintained at a mean blood pressure of 35 mmHg for 60 min, and then resuscitated with their own shed blood and adequate fluid. Mice were sacrificed at 30 min into hemorrhage and at 2, 4 or 24 hr post-hemorrhage to obtain serum samples. IL 6 and TNF levels were measured using cytokine dependent cellular assays. Using a quantitative Limulus amebocyte lysate assay, endotoxin levels were determined. TNF levels were significantly elevated at 30 min into hemorrhage, remaining so at 2 hr after resuscitation, but absent by 4 hr. Although there was a trend toward elevated IL 6 levels at 2 hr following hemorrhage, which was sustained up to 24 hr, the values were not significantly different from sham controls. When compared to controls, no marked increase in endotoxin was seen at any time point during or following hemorrhage. These results indicate that hemorrhage, in the absence of significant tissue trauma, causes enhanced TNF release which is not the result of increased endotoxin. 相似文献
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Roberto Jappelli Marilyn H. Perrin Kathy A. Lewis Joan M. Vaughan Christos Tzitzilonis Jean E. Rivier Wylie W. Vale Roland Riek 《PloS one》2014,9(1)
Corticotropin-Releasing Factor Receptors (CRFRs) are class B1 G-protein-coupled receptors, which bind peptides of the corticotropin releasing factor family and are key mediators in the stress response. In order to dissect the receptors'' binding specificity and enable structural studies, full-length human CRFR1α and mouse CRFR2β as well as fragments lacking the N-terminal extracellular domain, were overproduced in E. coli. The characteristics of different CRFR2β -PhoA gene fusion products expressed in bacteria were found to be in agreement with the predicted ones in the hepta-helical membrane topology model. Recombinant histidine-tagged CRFR1α and CRFR2β expression levels and bacterial subcellular localization were evaluated by cell fractionation and Western blot analysis. Protein expression parameters were assessed, including the influence of E. coli bacterial hosts, culture media and the impact of either PelB or DsbA signal peptide. In general, the large majority of receptor proteins became inserted in the bacterial membrane. Across all experimental conditions significantly more CRFR2β product was obtained in comparison to CRFR1α. Following a detergent screen analysis, bacterial membranes containing CRFR1α and CRFR2β were best solubilized with the zwitterionic detergent FC-14. Binding of different peptide ligands to CRFR1α and CRFR2β membrane fractions were similar, in part, to the complex pharmacology observed in eukaryotic cells. We suggest that our E. coli expression system producing functional CRFRs will be useful for large-scale expression of these receptors for structural studies. 相似文献
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Bradley Scott Perrin Jr. Toshiko Ichiye 《Journal of biological inorganic chemistry》2013,18(6):599-608
The reduction potential of an electron transfer protein is one of its most important functional characteristics. Although the type of redox site and the protein fold are the major determinants of the reduction potential of a redox-active protein, its amino acid sequence may tune the reduction potential as well. Thus, homologous proteins can often be divided into different classes, with each class characterized by a biological function and a reduction potential. Site-specific mutagenesis of the sequence determinants of the differences in the reduction potential between classes should change the reduction potential of a protein in one class to that of the other class. Here, a procedure is presented that combines energetic and bioinformatic analysis of homologous proteins to identify sequence determinants that are also good candidates for site-specific mutations, using the [4Fe–4S] ferredoxins and the [4Fe–4S] high-potential iron–sulfur proteins as examples. This procedure is designed to guide site-specific mutations or more computationally expensive studies, such as molecular dynamics simulations. To make the procedure more accessible to the general scientific community, it is being implemented into CHARMMing, a Web-based portal, with a library of density functional theory results for the redox site that are used in the setting up of Poisson–Boltzmann continuum electrostatics calculations for the protein energetics. 相似文献
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