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排序方式: 共有297条查询结果,搜索用时 31 毫秒
1.
Thermodynamic study of transthyretin association (wild‐type and senile forms) with heparan sulfate proteoglycan: pH effect and implication of the reactive histidine residue 下载免费PDF全文
Ambre Geneste Claire André Nadine Magy‐Bertrand Lydie Lethier Gharbi Tijani Yves Claude Guillaume 《Biomedical chromatography : BMC》2015,29(4):514-522
The tetramer destabilization of transthyretin into monomers and its fibrillation are phenomena leading to amyloid deposition. Heparan sulfate proteoglycan (HSPG) has been found in all amyloid deposits. A chromatographic approach was developed to compare binding parameters between wild‐type transthyretin (wtTTR) and an amyloidogenic transthyretin (sTTR). Results showed a greater affinity of sTTR for HSPG at pH 7.4 compared with wtTTR owing to the monomeric form of sTTR. Analysis of the thermodynamic parameters showed that van der Waals interactions were involved at the complex interface for both transthyretin forms. For sTTR, results from the plot representing the number of protons exchanged vs pH showed that the binding mechanism was pH‐dependent with a critical value at a pH 6.5. This observation was due to the protonation of a histidine residue as an imidazolium cation, which was not accessible when TTR was in its tetrameric structure. At pH >6.5, dehydration at the binding interface and several contacts between nonpolar groups of sTTR and HSPG were also coupled to binding for an optimal hydrogen‐bond network. At pH <6.5, the protonation of the His residue from sTTR monomer when pH decreased broke the hydrogen‐bond network, leading to its destabilization and thus producing slight conformational changes in the sTTR monomer structure. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
2.
Dr. Oumaïma Gharbi Dr. Mai T. T. Tran Prof. Mark E. Orazem Dr. Bernard Tribollet Dr. Mireille Turmine Dr. Vincent Vivier 《Chemphyschem》2021,22(13):1371-1378
The different contributions of the interfacial capacitance are identified in the case of passive materials or thin protective coatings deposited on the electrode surface. The method is based on a graphical analysis of the EIS results to determine both the passive-film capacitance in the high-frequency domain and the double-layer capacitance in the low-frequency domain. The proposed analysis is shown to be independent of the physicochemical origins of the frequency dispersion of the interfacial capacitances which results, from an analysis point of view of the experimental results, in the use of a constant-phase element However, for a correct evaluation of the thin-film properties such as its thickness, the high-frequency data must be corrected for the double-layer contribution. In particular, it is shown that if the double-layer capacitance gives a frequency-dispersed response, it is necessary to correct the high-frequency part for the double-layer constant-phase elements. This is first demonstrated on synthetic data and then used for the determination of the thickness of thin oxide film formed on Al in neutral pH solution. 相似文献
3.
Raca Todosijević Anis Mjirda Marko Mladenović Saïd Hanafi Bernard Gendron 《Optimization Letters》2017,11(6):1047-1056
In this paper, we present two general variable neighborhood search (GVNS) based variants for solving the traveling salesman problem with draft limits (TSPDL), a recent extension of the traveling salesman problem. TSPDL arises in the context of maritime transportation. It consists of finding optimal Hamiltonian tour for a given ship which has to visit and deliver products to a set of ports while respecting the draft limit constraints. The proposed methods combine ideas in sequential variable neighborhood descent within GVNS. They are tested on a set of benchmarks from the literature as well as on a new one generated by us. Computational experiments show remarkable efficiency and effectiveness of our new approach. Moreover, new set of benchmarks instances is generated. 相似文献
4.
Omer Anis Ajjampura C. Vinayaka Nurit Shalev Dvora Namdar Stalin Nadarajan Seegehalli M. Anil Ofer Cohen Eduard Belausov Jacob Ramon Einav Mayzlish Gati Hinanit Koltai 《Molecules (Basel, Switzerland)》2021,26(2)
Cannabis sativa contains more than 500 constituents, yet the anticancer properties of the vast majority of cannabis compounds remains unknown. We aimed to identify cannabis compounds and their combinations presenting cytotoxicity against bladder urothelial carcinoma (UC), the most common urinary system cancer. An XTT assay was used to determine cytotoxic activity of C. sativa extracts on T24 and HBT-9 cell lines. Extract chemical content was identified by high-performance liquid chromatography (HPLC). Fluorescence-activated cell sorting (FACS) was used to determine apoptosis and cell cycle, using stained F-actin and nuclei. Scratch and transwell assays were used to determine cell migration and invasion, respectively. Gene expression was determined by quantitative Polymerase chain reaction (PCR). The most active decarboxylated extract fraction (F7) of high-cannabidiol (CBD) C. sativa was found to contain cannabichromene (CBC) and Δ9-tetrahydrocannabinol (THC). Synergistic interaction was demonstrated between CBC + THC whereas cannabinoid receptor (CB) type 1 and type 2 inverse agonists reduced cytotoxic activity. Treatments with CBC + THC or CBD led to cell cycle arrest and cell apoptosis. CBC + THC or CBD treatments inhibited cell migration and affected F-actin integrity. Identification of active plant ingredients (API) from cannabis that induce apoptosis and affect cell migration in UC cell lines forms a basis for pre-clinical trials for UC treatment. 相似文献
5.
Synthesis,Crystal Structure,and Antibacterial Activity of 1,2,4‐Triazoles and 1,2,4‐Triazol‐3‐one 下载免费PDF全文
Bochra Ben Salah Najla Chaari Awatef Rekik Anis Ben Hsouna Mohamed Trigui Mohamed Kossentini 《Journal of heterocyclic chemistry》2015,52(6):1769-1775
A straightforward method has been developed for the synthesis of 1,2,4‐triazol‐3‐one 3 and 1,2,4‐triazoles 6a , 6b , 6c , 6d starting from N1‐substituted‐N1‐tosylhydrazonates 2 and hydrazine monohydrate. This methodology affords a number of 1,2,4‐triazol‐3‐one 3 and 1,2,4‐triazoles 6a , 6b , 6c , 6d in reasonable yields. The structures of all new compounds were elucidated using infrared, 1H and 13C NMR, high‐resolution mass spectrometry, elemental analysis, and the X‐ray crystallography (for compounds 3 and 6a ). Some of the newly synthesized compounds were screened for their antibacterial activity. 相似文献
6.
7.
Despite the increase in horizontal well applications, scaling fluid displacement in porous medium with horizontal wells is
yet to be fully investigated. Determining the conditions under which horizontal wells may lead to better oil recovery is of
great importance to the petroleum industry. In this paper, a numerical sensitivity study was performed for several well configurations.
The study is performed in order to reveal the functional relationships between the scaling groups governing the displacement
and the performance of immiscible displacements in homogeneous reservoirs produced by horizontal wells. These relationships
can be used as a quick prediction tool for the fractional oil recovery for any combinations of the scaling groups, thus eliminating
the need for the expensive fine-mesh simulations. In addition, they provide the condition under which a horizontal well configuration
may yield better recovery performance. These results have potential applications in modeling immiscible displacements and
in the scaling of laboratory displacements to field conditions. 相似文献
8.
9.
Jihen Mahfoudh Christelle Delaite Souhir Abid Rachid El Gharbi 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1002-1008
A series of random polyesteramides (PEAs) within a range of molar composition from 90/10 to 10/90 were synthesized by a direct melt polycondensation of lactic acid and β-alanine. Their structures were fully characterized by NMR spectroscopy. The resulting copolymers are amorphous; they are thermally stable to temperatures up to 254°C, and present increasing glass transition temperatures at increasing amide content. The copolymers were also characterized by FTIR and viscosimetry measurements. 相似文献
10.
In this paper, the spectral shape of the collision induced scattering is calculated in the dipole-induced-dipole approximation for the Raman symmetric vibrational band of optically isotropic molecules. Comparison is made with Rayleigh results. Experimental data for Rayleigh and v 1 Raman band of CF4 are discussed. 相似文献