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101.
Dr. Ralph P. G. Bosmans Jeroen M. Briels Dr. Lech‐Gustav Milroy Dr. Tom F. A. de Greef Prof. Maarten Merkx Prof. Luc Brunsveld 《Angewandte Chemie (International ed. in English)》2016,55(31):8899-8903
Supramolecular split‐enzyme complementation restores enzymatic activity and allows for on–off switching. Split‐luciferase fragment pairs were provided with an N‐terminal FGG sequence and screened for complementation through host‐guest binding to cucurbit[8]uril (Q8). Split‐luciferase heterocomplex formation was induced in a Q8 concentration dependent manner, resulting in a 20‐fold upregulation of luciferase activity. Supramolecular split‐luciferase complementation was fully reversible, as revealed by using two types of Q8 inhibitors. Competition studies with the weak‐binding FGG peptide revealed a 300‐fold enhanced stability for the formation of the ternary heterocomplex compared to binding of two of the same fragments to Q8. Stochiometric binding by the potent inhibitor memantine could be used for repeated cycling of luciferase activation and deactivation in conjunction with Q8, providing a versatile module for in vitro supramolecular signaling networks. 相似文献
102.
Structure,Physicochemical and Biological Properties of an Aqua (2,2′,2′′‐Nitrilotriacetato)‐oxidovanadium(IV) Salt with 4‐Methylpyridinium Cation
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Aleksandra Tesmar Dariusz Wyrzykowski Katarzyna Kazimierczuk Julia Kłak Szymon Kowalski Iwona Inkielewicz‐Stępniak Joanna Drzeżdżon Dagmara Jacewicz Lech Chmurzyński 《无机化学与普通化学杂志》2017,643(7):501-510
The crystal structure of a nitrilotriacetate (nta) oxidovanadium(IV) salt with 4‐methylpyridinium cation, [4‐Me(Py)H]+, of [4‐Me(Py)H][VO(nta)(H2O)] stoichiometry was determined. The complex comprises a discrete mononuclear [VO(nta)(H2O)]– coordination entity that can be rarely found among other known compounds containing nitrilotriacetate oxidovanadium(IV) moieties. The complex was characterized by spectroscopic (IR and EPR) methods, magnetic measurements, and thermogravimetry (TG‐FTIR). The stability of the title compound in aqueous solutions was investigated by using the potentiometric titration method. Furthermore, spectrophotometric (UV/Vis) studies have revealed that the compound is capable to scavenge the superoxide free radicals (O2 ? –) as well as stable organic radicals i.e. 2,2′‐azinobis(3‐ethylbenzothiazoline‐6 sulfonic acid) cation radical (ABTS+ ? ) and 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH ? ). Finally, biological properties of the complex studied were investigated in relation to its cytoprotective activity against the oxidative damage generated exogenously by using hydrogen peroxide in the HT22 hippocampal neuronal cell line (the MTT assay). Additionally, the biological action of the compound towards two human osteosarcoma HOS and MG‐63 cell lines (the MTT and BrdU tests) as well as the untransformed human osteoblast hFOB 1.19 cell line was tested. 相似文献
103.
The influence of the central donor atom of the oxydiacetate and thiodiacetate ligands (oxygen and sulphur atoms, respectively) on the thermodynamic parameters for complexation reactions of the Co2+ and Ni2+ ions has been investigated using the isothermal titration calorimetry (ITC) technique and density functional theory (DFT) computations. The polarized continuum (PCM) - solvation model was employed to describe the structural factors that govern the coordination modes of the ligands (mer or fac) in the solution. The differences in the binding enthalpies of the investigated complexes were discussed based on the results obtained both from the natural bond orbital (NBO) analysis and the second-order perturbation theory. 相似文献
104.
105.
Katarzyna Witkoś Katarzyna Lech Maciej Jarosz 《Journal of mass spectrometry : JMS》2015,50(11):1245-1251
The study concerns identification of photodegradation products of indigotin, indirubin and isoindigo. Experimental methodology consists of degradation of standard solutions of indigoids in a solar box and analysis of samples taken at different aging time by using capillary high‐performance liquid chromatography coupled with electrospray ionization tandem mass spectrometric and spectrophotometric detectors. Identification of the formed compounds was based on careful interpretation of the electrospray ionization MS/MS spectra. Apart from the well‐known degradation products of indigoids: isatin, isatoic anhydride and anthranilic acid, another seven species were also identified, and their proposed structures were confirmed by high‐resolution molecular masses measurements; according to the best knowledge of authors, they have not been reported so far. The obtained results formed the basis for postulating mechanism of the process. Moreover, the MRM (Multiple Reaction Monitoring) method was developed for the identification of natural dyes and their degradation products in textiles of historical value. Apart from such colorants as indigotin and flavonoids, also presence of degradation products of indigoids was confirmed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
106.
Dariusz Wyrzykowski Michał Wera Artur Sikorski Dagmara Jacewicz Lech Chmurzyński 《Central European Journal of Chemistry》2011,9(6):1096-1101
The crystal structure of 2-methylpyridinium tetrachloroferrate(III) was determined. The iron cation is tetracoordinated by
chloride anions, and it adopts a slightly distorted tetrahedral coordination with three angles smaller, two almost equal and
one larger than the tetrahedral. The compound is isostructural with its 3-, and 4-methylpyridinium analogues. The thermal
properties of 2-, 3- and 4-methylpyridinium tetrachloroferrates(III) have been studied using TG and DSC techniques. The compounds
exhibit a high stability in the melt.
相似文献
107.
Pazderski L Pawlak T Sitkowski J Kozerski L Szlyk E 《Magnetic resonance in chemistry : MRC》2011,49(5):237-241
(1)H, (13)C and (15)N NMR studies of iron(II), ruthenium(II) and osmium(II) bis-chelated cationic complexes with 2,2':6',2″-terpyridine ([M(terpy)(2) ](2+) ; M = Fe, Ru, Os) were performed. Significant shielding of nitrogen-adjacent H(6) and deshielding of H(3'), H(4') protons were observed, both effects being mostly expressed for Fe(II) compounds. The metal-bonded nitrogens were shielded, this effect being much larger for the outer N(1), N(1″) than the inner N(1') atoms, and enhanced in the Fe(II) → Ru(II) → Os(II) series. 相似文献
108.
Agnieszka Iwan Lech Gorecki Damian Pociecha 《Journal of Thermal Analysis and Calorimetry》2012,110(1):43-49
Thermal properties of two azomethine liquid crystals with a benzothiazole core were synthesized and investigated by applied Mettler-Toledo AG equipment (TG/DSC). Azomethines with benzothiazole core was obtained by nucleophilic addition of benzothiazole-2-carboxaldehyde in N,N-dimethylacetamide (DMA) solution with 4-(heptadecafluoroctyl)aniline (BTA1) or 4-hexadecylaniline (BTA2). The differential scanning calorimetry (DSC) was employed to evaluate their phase transitional behavior. Variable heating and cooling rates were used to study liquid crystalline properties of azomethines with benzothiazole core. Compound BTA1 exhibited liquid crystalline properties, while BTA2 is non-mesogenic. Three or four endothermic DSC peaks were observed for both compounds during heating process with the rate 0.5?°C/min. The mesophase was identified and confirmed by XRD study and polarized optical microscopy (POM) too. The thermal stability was determined by thermogravimetric analysis (TG). The temperatures of 5% mass loss (T 5%) of BTA1 and BTA2 range from 212 to 317?°C in nitrogen. 相似文献
109.
Lech Maligranda 《Positivity》2013,17(3):707-710
The $K$ -functional of Peetre is calculated for $p$ -convexifications of normed ideal space as an answer to Lozanovski? problem. 相似文献
110.
Grzegorz Gabor Lech Górniewicz Mirosław Ślosarski 《Set-Valued and Variational Analysis》2009,17(1):1-19
A concept of generalized topological essentiality for a large class of multivalued maps in topological vector Klee admissible
spaces is presented. Some direct applications to differential equations are discussed. Using the inverse systems approach
the coincidence point sets of limit maps are examined. The main motivation as well as main aim of this note is a study of
fixed points of multivalued maps in Fréchet spaces. The approach presented in the paper allows to check not only the nonemptiness
of the fixed point set but also its topological structure.
相似文献