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381.
Stefan Sulmann Dr. Daniele Dell'Orco Valerio Marino Dr. Petra Behnen Prof. Dr. Karl‐Wilhelm Koch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6756-6762
Fundamental components of signaling pathways are switch modes in key proteins that control start, duration, and ending of diverse signal transduction events. A large group of switch proteins are Ca2+ sensors, which undergo conformational changes in response to oscillating intracellular Ca2+ concentrations. Here we use dynamic light scattering and a recently developed approach based on surface plasmon resonance to compare the protein dynamics of a diverse set of prototypical Ca2+‐binding proteins including calmodulin, troponin C, recoverin, and guanylate cyclase‐activating protein. Surface plasmon resonance biosensor technology allows monitoring conformational changes under molecular crowding conditions, yielding for each Ca2+‐sensor protein a fingerprint profile that reflects different hydrodynamic properties under changing Ca2+ conditions and is extremely sensitive to even fine alterations induced by point mutations. We see, for example, a correlation between surface plasmon resonance, dynamic light scattering, and size‐exclusion chromatography data. Thus, changes in protein conformation correlate not only with the hydrodynamic size, but also with a rearrangement of the protein hydration shell and a change of the dielectric constant of water or of the protein–water interface. Our study provides insight into how rather small signaling proteins that have very similar three‐dimensional folding patterns differ in their Ca2+‐occupied functional state under crowding conditions. 相似文献
382.
Guido Crisponi Annalisa Dean Valerio Di Marco Joanna I. Lachowicz Valeria M. Nurchi Maurizio Remelli Andrea Tapparo 《Analytical and bioanalytical chemistry》2013,405(2-3):585-601
Our objective is to illustrate the activity of the groups operating in Italy involved in identification and study of new chelating agents, mainly intended for treatment of human pathology correlated with metal overload. The objective of “chelation therapy” is removal of toxic metal ions from the human body or attenuation of their toxicity by transforming them into less toxic compounds or by dislocating them from the site at which they exert a toxic action. Because most of this research activity is related to chelating agents for iron and aluminium, diseases related to these two metal ions are briefly treated. Iron overload is the most common metal toxicity disease worldwide. The toxicity of aluminium in dialysis patients was a serious problem for haemodialysis units in the seventies and eighties of the last century. In particular, this review focuses on research performed by the group at Cagliari and Ferrara, and by that at Padova. The former is studying, above all, bisphosphonate and kojic acid derivatives, and the latter is investigating 3,4-hydroxypyridinecarboxylic acids with differently substituted pyridinic rings. Figure
Aim of this paper is to illustrate the research on different classes of ligands, which are intended as possible chelating agents for the treatment of human pathologies correlated to iron and aluminium overload. 相似文献
383.
In this work we are investigating dopant environments in LiYF 4 -LiREF 4 (RE=rare-earth cations) solid solutions, via EXAFS. The main aims are to identify the local environmental symmetry and the average lattice distortion as a function of the concentration and the type of the RE ion. LiY 1 m x RE x F 4 (RE=Gd or Lu) (0< x <1) single crystals were grown by the Czochralski technique under argon or CF 4 atmosphere, crystal-pulling rates were 0.6-1 v mm/h for <100>-oriented boules, with 8-25 v rpm rotation rates. Most of the crystals were also codoped with 2.7 v mol% of neodymium in the melt. EXAFS measurements were performed in transmission and fluorescence modes in the synchrotron XAS line of the LNLS, Campinas, Brazil, in and above the L III absorption edges of the RE ions. The samples were prepared as powder films, for the transmission mode measurements, and as powder or single crystals for fluorescence mode measurements. The WINXAS program was used for data reduction and fitting, and the FEFF6 package was used for the simulations of the spectra. The EXAFS oscillation curves were obtained by standard procedure. 相似文献
384.
Abstract The computer modelling technique was used in the present work to study the intrinsic defects and the migration processes in KY3F10. The main intrinsic disorder was found to be F Frenkel pairs but at higher temperatures it is possible that KF pseudo-Schottky defects could also be present in the material. The ionic conduction process is mainly due to the fluorine ions migrating via both vacancy and interstitialcy mechanisms. 相似文献
385.
386.
Easily handled and nontoxic Bi(OTf)3 is a powerful activator for trichloro- and (N-phenyl)trifluoroacetimidate glycosyl donors. This catalyst allows glycosidations to be performed at low temperatures in very short times. Rewarding yields were obtained from a wide range of donors of varying reactivity. 相似文献
387.
Engineering of CH3NH3PbI3 Perovskite Crystals by Alloying Large Organic Cations for Enhanced Thermal Stability and Transport Properties 下载免费PDF全文
Wei Peng Dr. Xiaohe Miao Valerio Adinolfi Dr. Erkki Alarousu Dr. Omar El Tall Dr. Abdul‐Hamid Emwas Dr. Chao Zhao Grant Walters Jiakai Liu Olivier Ouellette Dr. Jun Pan Dr. Banavoth Murali Prof. Edward H. Sargent Prof. Omar F. Mohammed Prof. Osman M. Bakr 《Angewandte Chemie (International ed. in English)》2016,55(36):10686-10690
The number of studies on organic–inorganic hybrid perovskites has soared in recent years. However, the majority of hybrid perovskites under investigation are based on a limited number of organic cations of suitable sizes, such as methylammonium and formamidinium. These small cations easily fit into the perovskite's three‐dimensional (3D) lead halide framework to produce semiconductors with excellent charge transport properties. Until now, larger cations, such as ethylammonium, have been found to form 2D crystals with lead halide. Here we show for the first time that ethylammonium can in fact be incorporated coordinately with methylammonium in the lattice of a 3D perovskite thanks to a balance of opposite lattice distortion strains. This inclusion results in higher crystal symmetry, improved material stability, and markedly enhanced charge carrier lifetime. This crystal engineering strategy of balancing opposite lattice distortion effects vastly increases the number of potential choices of organic cations for 3D perovskites, opening up new degrees of freedom to tailor their optoelectronic and environmental properties. 相似文献
388.
389.
Domenico Cassano Melissa Santi Valentina Cappello Stefano Luin Giovanni Signore Valerio Voliani 《Particle & Particle Systems Characterization》2016,33(11):818-824
Accumulation of inorganic nanostructures in the excretory system organs increases their likelihood of toxicity and interference with common medical diagnoses. Thus, one of the major concerns regarding their clinical translation is related to their persistence in organisms. Here the authors demonstrate that nano‐architectures composed by hollow silica nanocapsules embedding arrays of ultrasmall gold nanoparticles undergo biodegradation in cellular environment affording small, potentially clearable building blocks. Furthermore, the authors present their exploitation in glutathione‐triggered release of covalently loaded cisplatin prodrug. This endogenously triggered release leads to high cytotoxicity to human pancreatic carcinoma cells, setting the way for promising applications to synergistic dual chemo/radio‐therapy and radio‐imaging. 相似文献
390.
Simůnek P Lusková L Svobodová M Bertolasi V Lycka A Machácek V 《Magnetic resonance in chemistry : MRC》2007,45(4):330-339
The reaction of 3-phenylaminocyclopent-2-en-1-one with 4-methyl, 4-methoxy and 4-chlorobenzenediazonium tetrafluoroborates was used to prepare the azo coupling products 3a-c. It was found that these compounds are present in both CDCl(3) solution and solid phase practically exclusively as (E)-3-phenylamino-2-(4-subst.phenyldiazenyl)cyclopent-2-en-1-ones with N--H...N intramolecular hydrogen bond. The substitution of the phenyl residue of the diazonium salt has no effect on the position of the tautomeric equilibrium. On the other hand, the compounds 4a, b formed by the reaction of 3-phenylamino-1H-inden-1-one with 4-methylbenzene- or benzenediazonium tetrafluoroborates exist in CDCl(3) solution and in solid phase as hydrazone compounds. In the solution they occur as a mixture of three forms, out of which two were identified as E/Z isomers with different types of hydrogen bonds. Compound 5 formed by the reaction of 3-amino-5,5-dimethylcyclohex-2-en-1-one with 4-methoxybenzenediazonium tetrafluoroborate is converted into a stable hydrochloride 5.HCl on standing in CHCl(3) solution; this product exhibits a high degree of delocalization of the positive charge. Its structure was studied by means of X-ray. 相似文献