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排序方式: 共有69条查询结果,搜索用时 15 毫秒
1.
Jo E Sanna MG Gonzalez-Cabrera PJ Thangada S Tigyi G Osborne DA Hla T Parrill AL Rosen H 《Chemistry & biology》2005,12(6):703-715
The essential role of the sphingosine 1-phosphate (S1P) receptor S1P(1) in regulating lymphocyte trafficking was demonstrated with the S1P(1)-selective nanomolar agonist, SEW2871. Despite its lack of charged headgroup, the tetraaromatic compound SEW2871 binds and activates S1P(1) through a combination of hydrophobic and ion-dipole interactions. Both S1P and SEW2871 activated ERK, Akt, and Rac signaling pathways and induced S1P(1) internalization and recycling, unlike FTY720-phosphate, which induces receptor degradation. Agonism with receptor recycling is sufficient for alteration of lymphocyte trafficking by S1P and SEW2871. S1P(1) modeling and mutagenesis studies revealed that residues binding the S1P headgroup are required for kinase activation by both S1P and SEW2871. Therefore, SEW2871 recapitulates the action of S1P in all the signaling pathways examined and overlaps in interactions with key headgroup binding receptor residues, presumably replacing salt-bridge interactions with ion-dipole interactions. 相似文献
2.
Micelles of different amphiphiles adopt different shapes and internal packing arrangements in water, depending on their chemical
structures and the conditions of the medium. Two microenvironmental features, namely the polarity and the microviscosity that
the aggregate offers to a solubilized molecule, have been monitored using extrinsic fluorescence probes. While the differences
between micelles of spherical and rod-like shapes are not always distinct, stacked micelles and peptide micelles offer distinctly
lower polarity and higher microviscosity to solubilizates than the others. 相似文献
3.
Effects of nutrients and temperature on lipid and fatty acid production in the diatomHantzshia DI-60
Sriharan Shobha bagga Davinderjit Sriharan T. P. 《Applied biochemistry and biotechnology》1990,24(1):309-316
Applied Biochemistry and Biotechnology - The ability of microalgae to accumulate considerable amounts of lipids has led to an increase in research on the cultivation of these organisms for the... 相似文献
4.
Eng William Palumbo Anthony V. Sriharan Shobha Strandberg G. W. 《Applied biochemistry and biotechnology》1991,(1):887-899
The effect of methanol on trichloroethylene (TCE) degradation by mixed and pure methylotrophic cultures was examined in batch
culture experiments. Methanol was found to relieve growth inhibition ofMethylosinus trichosporium (OB3b) at high (14 mg/L) TCE concentrations. Degradation of TCE was determined by both radiolabeling and gas chromatography
techniques. When cultures were grown on methanol over 10 to 14 d with 0.3 mg/L TCE, OB3b degraded 16.89 ±0.82% (mean± SD)
of the TCE, and a mixed culture (DT type II) degraded 4.55±0.11%. Mixed culture (JS type I) degraded 4.34±0.06% of the TCE.
When grown on methane with 0.3 mg/L TCE, 32.93±2.01% of the TCE was degraded by OB3b, whereas the JS culture degraded 24.3
±1.38% of the TCE, and the DT culture degraded 34.3 ±2.97% of the TCE. The addition of methanol to cultures grown on methane
reduced TCE degradation to 16.21 ±1.17% for OB3b and to 5.08±0.56% for JS. Although methanol reduces the toxicity of TCE to
the cultures, biodegradation of TCE cannot be sustained in methanol-grown cultures. Since high TCE concentrations appear to
inhibit methane uptake and growth, we suggest the primary toxicity of TCE is directed towards the methane monooxygenase. 相似文献
5.
6.
The optimisation of ultrasonic cleaning procedures for dairy fouled ultrafiltration membranes 总被引:3,自引:0,他引:3
Muthukumaran S Kentish S Lalchandani S Ashokkumar M Mawson R Stevens GW Grieser F 《Ultrasonics sonochemistry》2005,12(1-2):29-35
Ultrafiltration (UF) of whey is a major membrane based process in the dairy industry. However, commercialization of this application has been limited by membrane fouling, which has a detrimental influence on the permeation rate. There are a number of different chemical and physical cleaning methods currently used for cleaning a fouled membrane. It has been suggested that the cleaning frequency and the severity of such cleaning procedures control the membrane lifetime. The development of an optimal cleaning strategy should therefore have a direct implication on the process economics. Recently, the use of ultrasound has attracted considerable interest as an alternative approach to the conventional methods. In the present study, we have studied the ultrasonic cleaning of polysulfone ultrafiltration membranes fouled with dairy whey solutions. The effects of a number of cleaning process parameters have been examined in the presence of ultrasound and results compared with the conventional operation. Experiments were conducted using a small single sheet membrane unit that was immersed totally within an ultrasonic bath. Results show that ultrasonic cleaning improves the cleaning efficiency under all experimental conditions. The ultrasonic effect is more significant in the absence of surfactant, but is less influenced by temperature and transmembrane pressure. Our results suggest that the ultrasonic energy acts primarily by increasing the turbulence within the cleaning solution. 相似文献
7.
We study the action of translation operators on wavelet subspaces. This action gives rise to an equivalence relation on the
set of all wavelets. We show by explicit construction that each of the associated equivalence classes is non-empty. 相似文献
8.
Sneha Karmarkar P. V. Khadikar Vijay K. Agrawal Keshav C. Mathur Manorama Mandloi Shobha Joshi 《Journal of Chemical Sciences》2000,112(1):43-49
Proton-ligand formation constants of salicylhydroxamic acids (SHA) and their nuclear substituted derivatives have been estimated
topologically using the normalized Wiener index, referred to as mean square Wiener index (Wms). Regression analysis of the
data indicates that Wms can be used successfully for estimating and monitoring proton-ligand formation constants. 相似文献
9.
Nazar Mohammed Gabra Bakheit Mustafa Yata Praveen Kumar C. Shobha Devi A. Srishailam P. Venkat Reddy Kotha Laxma Reddy S. Satyanarayana 《Journal of fluorescence》2014,24(1):169-181
A new ligand 3-(1H-imidazo[4,5-f][1,10]phenanthrolin-2yl)phenylboronic acid and its (IPPBA) three ruthenium(II) complexes [Ru(phen)2(IPPBA)](ClO4)2 (1), [Ru(bpy)2(IPPBA)](ClO4)2 (2) and [Ru(dmb)2(IPPBA)](ClO4)2 (3) have been synthesized and characterized by elemental analysis, UV/VIS, IR, 1H-NMR,13C-NMR and mass spectra. The binding behaviors of the three complexes to calf thymus DNA were investigated by absorption spectra, emission spectroscopy, viscosity measurements, thermal denaturation and photoactivated cleavage. The DNA-binding constants for complexes 1, 2 and 3 have been determined to be 7.9?×?105 M?1, 6.7?×?105 M?1 and 2.9?×?105 M?1. The results suggest that these complexes bound to double-stranded DNA in an intercalation mode. Upon irradiation at 365 nm, three ruthenium complexes were found to promote the cleavage of plasmid pBR322 DNA from super coiled form ? to nicked form ??. Further in the presence of Co2+, the emission of DNA–Ru(ΙΙ) complexes can be quenched. And when EDTA was added, the emission was recovered. The experimental results show that all three complexes exhibited the “on–off–on” properties of molecular “light switch”. The highest Cytotoxicity potential of the complex1 was observed on the Human alveolar adenocarcinoma (A549) cell line. Good agreement was generally found between the spectroscopic techniques and molecular docked model which provides further evidence of groove binding. 相似文献
10.
Floating spherical Gaussian orbital model is used to discuss the average electric polarisabilities and magnetic susceptibilities
of a series of hydrocarbons. It has been noticed that the core contributions are negligibly small and these quantities (average
electric polarisabilities and magnetic susceptibilities) can be well estimated from contributions localised on bond Gaussians. 相似文献