排序方式: 共有113条查询结果,搜索用时 15 毫秒
81.
This paper investigates the adsorption of bovine serum albumin (BSA) and bovine hemoglobin (BHb) model proteins onto novel thymine-functionalized polystyrene (PS-VBT) microspheres, in comparison with polystyrene (PS) microspheres. Maximum adsorption was obtained for both proteins near their corresponding isoelectric points (pI at pH = 4.7 for BSA and 7.1 for BHb). FTIR and adsorption isotherm analysis demonstrated that, although both proteins were physisorbed onto PS through nonspecific hydrophobic interactions, adsorption onto the functionalized copolymers occurred by both physisorption and chemisorption via hydrogen bonding. FTIR analysis also indicated conformational changes in the secondary structure of BSA and BHb adsorbed onto PS, whereas little or no conformation change was seen in the case of adsorption onto PS-VBT. Atomic force microscopy (AFM), consistent with the isotherm results, also demonstrated monolayer adsorption for both proteins. AFM images of BSA adsorbed onto copolymers with 20 mol % surface VBT loading showed exclusively end-on orientation. Adsorption onto copolymers with lower functionality showed mixed end-on and side-on orientation modes of BSA, and only the side-on orientation was observed on PS. The AFM results agreed well with theoretically calculated and experimentally obtained adsorption capacities. AFM together with calculated and observed adsorption capacity data for BHb indicated that this protein might be highly compressed on the copolymer surface. Adsorption from a binary mixture of BSA and BHb onto PS-VBT showed good separation at pH=7.0; approximately 90% of the adsorbed protein was BHb. The novel copolymers have potential applications in biotechnology. 相似文献
82.
Fabrication and optimization of methylphenoxy substituted polyphosphazene nanofibers for biomedical applications 总被引:3,自引:0,他引:3
Nair LS Bhattacharyya S Bender JD Greish YE Brown PW Allcock HR Laurencin CT 《Biomacromolecules》2004,5(6):2212-2220
Electrospinning has developed as a unique and versatile process to fabricate ultrathin fibers in the form of nonwoven meshes or as oriented arrays from a variety of polymers. The very small dimension of these fibers can generate a high surface area, which makes them potential candidates for various biomedical and industrial applications. The objective of the present study was to develop nanofibers from polyphosphazenes, a class of inorganic-organic polymers known for high biocompatibility, high-temperature stability, and low-temperature flexibility. Specifically, we evaluated the feasibility of developing bead-free nonwoven nanofiber mesh from poly[bis(p-methylphenoxy)phosphazene] (PNmPh) by electrospinning. The effect of process parameters such as nature of solvent, concentration of the polymer solution, effect of needle diameter, and applied potential on the diameter and morphology (beaded or bead-free) of resulting nanofibers were investigated. It was found that solution of PNmPh in chloroform at a concentration range of 7% (wt/v) to 9% (wt/v) can be readily electrospun to form bead-free fibers at room temperature. The mean diameter of the fibers obtained under optimized spinning condition was found to be approximately 1.2 microm. The bead-free, cylindrical nanofibers formed under the optimized condition showed a slightly irregular surface topography with indentations of a few nanometer scale. Further, the electrospun nanofiber mats supported the adhesion of bovine coronary artery endothelial cells (BCAEC) as well as promoted the adhesion and proliferation of osteoblast like MC3T3-E1 cells. 相似文献
83.
Two new species of Eimeria were found from faecal samples of ten green peacocks (Pavo muticus) collected at Al-Kharj area, a central region of Saudi Arabia. Sporulated oocysts of Eimeria mutica n.sp. are ellipsoidal 23.1×17.4 (22.4–25.0×16.7–18.9) μm, with a smooth bilayered wall. A micropyle and bilobed polar body are present, but without an oocyst residuum. The sporocyst is an elongated-ovoid 13.7×6.2 (12.0–14.2×5.4–6.7) μm, with a Stieda body and a residuum. Sporulated oocysts of E. kharjensis n.sp. are subspherical 20.3×17.7 (19.0–21.5×16.2–18.7) μm, with a two layered wall and a single polar body. The micropyle is covered by a dome-shaped cap and the sporocyst is an elongate-ovoid 12.7×6.3 (11.9–13.5×5.4–6.8) μm, with a Stieda body. The sporocyst residuum is present as several small granules. 相似文献
84.
Simone Pellegrino Natalia Demeshkina Eder Mancera-Martinez Sergey Melnikov Angelita Simonetti Alexander Myasnikov Marat Yusupov Gulnara Yusupova Yaser Hashem 《Journal of molecular biology》2018,430(17):2677-2687
One of the most critical steps of protein biosynthesis is the coupled movement of mRNA, which encodes genetic information, with tRNAs on the ribosome. In eukaryotes, this process is catalyzed by a conserved G-protein, the elongation factor 2 (eEF2), which carries a unique post-translational modification, called diphthamide, found in all eukaryotic species. Here we present near-atomic resolution cryo-electron microscopy structures of yeast 80S ribosome complexes containing mRNA, tRNA and eEF2 trapped in different GTP-hydrolysis states which provide further structural insights into the role of diphthamide in the mechanism of translation fidelity in eukaryotes. 相似文献
85.
Yaser Hassan Dewir Debasis Chakrabarty Mohammed Babar Ali Nisha Singh Eun-Joo Hahn Kee-Yoeup Paek 《Plant Cell, Tissue and Organ Culture》2007,90(3):225-235
Hormonal control of flower induction and inflorescence development in vitro was investigated in Spathiphyllum. The effects of gibberellic acid (GA3) and sucrose on inflorescence development were studied in plantlets regenerated in tissue culture. GA3 was mandatory for the shift from the vegetative to the reproductive stage. The effect of sucrose concentration on inflorescence
bud development was studied in plantlets cultured in MS medium supplemented with 10 mg l−1 GA3. Sucrose concentration at 3 or 6% induced inflorescence development in, respectively, 83–85% of the plantlets. The effect
of GA3 and sucrose on inflorescence differentiation and development were also recorded in liquid culture using air-lift bioreactor.
The best response was found in the same medium which was standardized as an optimum for solid culture, but the results were
better than solid culture. In order to study the relationship between glutathione (GSH) and flowering, we also measured the
oxidized and reduced GSH content in leaves throughout the culture period on 2 weeks interval. The GSH accumulation was more
after 4 weeks until 6 weeks in GA3 treated plantlets. Similarly, glutathione reductase which is involved in the recycling of reduced GSH providing a constant
intracellular level of GSH, was also higher in GA3 treated plantlets. The transient increase in GSH contents also correlated with the changes in measured γ-glutamylcysteine synthetase (γ-ECS) activity over the same period. The antioxidant enzyme activity in GA3 treated plantlets also suggests that the plants suffered increased oxidative stress during the period of GA3 treatment which subsequently increases GSH synthesis through activation of γ-ECS and this promotes flowering by increasing
endogenous GSH. 相似文献
86.
SwS: a solvation web service for nucleic acids 总被引:2,自引:0,他引:2
SwS, based on a statistical analysis of crystallographic structures deposited in the NDB, is designed to provide an exhaustive overview of the solvation of nucleic acid structural elements through the generation of 3D solvent density maps. A first version (v1.0) of this web service focuses on the interaction of DNA, RNA and hybrid base pairs linked by two or three hydrogen bonds with water, cations and/or anions. Data provided by SwS are updated on a weekly basis and can be used by: (i) those involved in molecular dynamics simulation studies for validation purposes; (ii) crystallographers for help in the interpretation of solvent density maps; and all those involved in (iii) drug design and, more generally, in (iv) nucleic acid structural studies. SwS provides also statistical data related to the frequency of occurrence of different types of base pairs in crystallographic structures and the conformation of the involved nucleotides. This web service has been designed to allow a maximum of flexibility in terms of queries and has also been developed with didactic considerations in mind. AVAILABILITY: http://www-ibmc.u-strasbg.fr/arn/sws.html 相似文献
87.
Rakhshan Kamran Azizi Yaser Naderi Nasim Ghardashi Afousi Alireza Aboutaleb Nahid 《International journal of peptide research and therapeutics》2019,25(2):613-621
International Journal of Peptide Research and Therapeutics - Emerging evidence has shown that ELA peptide plays a pivotal role in cardiac development and modulation of vascular and cardiac... 相似文献
88.
A facile and convenient synthesis of new pyridazines suitable for use as antimicrobial agents was reported. The hydrazide intermediate was coupled with various benzaldehydes and/or acetophenones and cyclized instantaneously to afford target pyridazine derivatives. The structures of new pyridazines were confirmed by IR, 1H‐ and 13C‐NMR, elemental analysis in addition to representative LC/MS. Antimicrobial activity was screened against 10 bacterial and fungal strains. The new pyridazines showed strong to very strong antibacterial activity against Gram‐negative (GNB) bacteria, while none of them showed significant antifungal activity at the same concentration range. Chloro derivatives exhibited the highest antibacterial activity with MICs (0.892–3.744 μg/mL) lower than that of chloramphenicol (2.019–8.078 μg/mL) against E. coli, P. aeruginosa, and S. marcescens. Prediction of ADME parameters, pharmacokinetics, and substrate promiscuity revealed that these new pyridazines could be promising drug candidates. Cytotoxic studies on rat hepatocytes showed how much safe these new pyridazines on living organisms (IC50>64 μg/mL). MOE docking studies showed a good overlay of these new pyridazines with co‐crystallized ligand within an E. coli DNA gyrase subunit B active sites (4KFG). 相似文献
89.
Farzaneh Darbeheshti Mojdeh Mahdiannasser Zahra Noroozi Zahra Firoozi Behnam Mansoori Abdolreza Daraei Milad Bastami Ziba Nariman-Saleh-Fam Elahe Valipour Yaser Mansoori 《Journal of cellular and molecular medicine》2021,25(24):11322-11332
The aggressive and highly metastatic nature of triple-negative breast cancer (TNBC) causes patients to suffer from the poor outcome. HIF-1 signalling pathway is a prominent pathway that contributes to angiogenesis and metastasis progression in tumours. On the contrary, the undeniable importance of circular RNAs (circRNAs) as multifunctional non-coding RNAs (ncRNAs) has been identified in breast cancer. These ncRNAs owing to their high stability and specificity have been becoming a hotspot in cancer researches. circRNAs act as competing endogenous RNAs (ceRNAs) and compete with mRNAs for shared miRNAs, thus modulate gene expression. Since the most dysregulated biological functions in TNBC are associated with cellular invasion, understanding the molecular pathogenesis of these processes is a crucial step towards the development of new treatment approaches. The purpose of this study is to undermine the circRNA-associated ceRNA network involved in HIF-1 signalling in TNBC using an integrative bioinformatics approach. In the next step, the novel circ_0047303-mediated ceRNA regulatory axes have been extracted and validated across TNBC samples. We show that circ_0047303 has the highest degree in the circRNA-associated ceRNA network and shows a significant up-expression in TNBC. Moreover, our results suggest that circ_0047303 could mediate the upregulation of key angiogenesis-related genes, including HIF-1, EIF4E2 and VEGFA in TNBC through sponging the tumour-suppressive miRNAs. The circ_0047303 could be a promising molecular biomarker and/or therapeutic target for TNBC. 相似文献
90.
The present study demonstrates the ability to produce green biocellulose nanofibers using the renewable resources of agriculture residues. Locally grown wheat straws (WS) were hydrolyzed under different conditions. Their hydrolysates were utilized to produce the nanofibers in separate hydrolysis fermentation process by Gluconacetobacter xylinus strain bacterium. Highest biocellulose production of ~10.6 g/L was achieved with samples that were enzymatically hydrolyzed. Moreover, acidic hydrolyzed WS produced up to 9.7 g/L, with total sugar concentrations in culture media of 43 g/L. Generally, enzymatic hydrolysis of WS resulted in more total sugar concentration than the acidic hydrolysis (i.e., 52.12 g/L), while water hydrolysis produced the least. This can be related to utilizing Xylanase in addition to Cellulase and Beta-glucosidase that helps to hydrolyse WS dry basis of cellulose and hemicelluloses. Sugar mixtures produced under all hydrolysis conditions were mainly composed of glucose and xylose with average percentages of 56 and 28 %, respectively. Acidic hydrolysis at higher acid concentration, as well as soaking WS in the acidic solution for longer time, improved the total sugar concentration in the culture media by 18 %. Conducting thermal treatment at more intense conditions of higher temperature or heating time improved the total sugar produced with acidic hydrolysis. These conditions, however, resulted in further production of furfural, which considerably affected bacterial cells proliferation. This resulted in lowest sugar consumption in the range of 62–64 % that affected final BC production. 相似文献