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排序方式: 共有309条查询结果,搜索用时 78 毫秒
301.
Letizia Pontoriero Marco Schiavina Dr. Maria Grazia Murrali Prof. Roberta Pierattelli Prof. Isabella C. Felli 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(42):18696-18704
Many properties of intrinsically disordered proteins (IDPs), or protein regions (IDRs), are modulated by the nature of amino acid side chains as well as by local solvent exposure. We propose a set of exclusively heteronuclear NMR experiments to investigate these features in different experimental conditions that are relevant for physiological function. The proposed approach is generally applicable to many IDPs/IDRs whose assignment is available in the Biological Magnetic Resonance Bank (BMRB) to investigate how their properties are modulated by different, physiologically relevant conditions. The experiments, tested on α-synuclein, are then used to investigate how α-synuclein senses Ca2+ concentration jumps associated with the transmission of nerve signals. Novel modules in the primary sequence of α-synuclein optimized for calcium sensing in highly flexible, disordered protein segments are identified. 相似文献
302.
Baccarelli I Gianturco FA Grandi A Sanna N Lucchese RR Bald I Kopyra J Illenberger E 《Journal of the American Chemical Society》2007,129(19):6269-6277
Electron attachment experiments are carried out on the beta-d-ribose molecule in the gas phase for the energy region around 8 eV, and clear fragmentation products are observed for different mass values. A computational analysis of the relevant dynamics is also carried out for the beta-d-ribose in both the furanosic and pyranosic form as gaseous targets around that energy range. The quantum scattering attributes obtained from the calculations reveal in both systems the presence of transient negative ions (TNIs). An analysis of the spatial features of the excess resonant electron, together with the computation and characterization of the target molecular normal modes, suggests possible break-up pathways of the initial, metastable molecular species. 相似文献
303.
Gemma S Colombo L Forloni G Savini L Fracasso C Caccia S Salmona M Brindisi M Joshi BP Tripaldi P Giorgi G Taglialatela-Scafati O Novellino E Fiorini I Campiani G Butini S 《Organic & biomolecular chemistry》2011,9(14):5137-5148
Here we describe the identification and preliminary characterization of a new class of pyrrolo(imidazo)quinoxaline hydrazones as florescent probes for Aβ(1-42) fibrils. All the newly developed compounds were able to bind amyloid fibrils formed in vitro and some of them displayed an increase of their fluorescence upon binding. When tested on brain tissue preparations presenting Aβ deposits, the described hydrazones selectively stained amyloid structures and did not display aspecific binding. The hydrazones did not show antifibrillogenic activity and electron microscopy analysis revealed that they do not interfere with fibrils structure. The described pyrrolo(imidazo)quinoxalines could be useful for studying amyloid structures in vitro. Moreover, their experimentally proven ability to cross the blood-brain barrier in mouse opens the possibility of developing these compounds as potential amyloid imaging agents for in vivo applications. 相似文献
304.
The first total synthesis of the dimeric alkaloid pigment scytonemin is described. The key transformations in its synthesis from 3-indole acetic acid are a Heck carbocyclization and a Suzuki-Miyaura cross-coupling, orchestrated in a stereospecific tandem fashion, followed by a biosynthetically inspired oxidative dimerization. The tandem sequence generates a tetracyclic (E)-3-(arylidene)-3,4-dihydrocyclopenta[b]indol-2(1H)-one that is subsequently dimerized into the unique homodimeric core structure of scytonemin. 相似文献
305.
Diana Sannino Vincenzo Vaiano Paolo Ciambelli Isabella Zama Giacomo Gorni 《Journal of Thermal Analysis and Calorimetry》2013,111(1):453-458
The aim of this work is to evaluate the amount of N719 dye in TiO2 films for DSSCs by thermogravimetric analysis coupled with mass spectrometry (TG-MS) in comparison with the traditional method based on the dye extraction in NaOH solutions. The characterization was carried out on TiO2 films applied on FTO glasses by automatic screen printing method. For all the samples, TG-MS showed three well defined steps. The first, below 100 °C and coupled to an endothermic signal was due to water release. From 200 to about 300 °C, there was the release of CO2 coming from decarboxylation reaction of N719. The last exothermic step was due to the combustion of organic residues. As the decarboxylation reaction occurs with release of 4 moles of CO2 per mole of N719, it was used to determine the dye loading of the samples that resulted in the range 7?15 wt% well agreeing the relevant content of dye obtained by desorption with NaOH. 相似文献
306.
307.
Dr. Matteo Capone Dr. Abhishek Sirohiwal Prof. Massimiliano Aschi Dr. Dimitrios A. Pantazis Prof. Isabella Daidone 《Angewandte Chemie (International ed. in English)》2023,62(16):e202216276
Photosystem-II (PSII) is a multi-subunit protein complex that harvests sunlight to perform oxygenic photosynthesis. Initial light-activated charge separation takes place at a reaction centre consisting of four chlorophylls and two pheophytins. Understanding the processes following light excitation remains elusive due to spectral congestion, the ultrafast nature, and multi-component behaviour of the charge-separation process. Here, using advanced computational multiscale approaches which take into account the large-scale configurational flexibility of the system, we identify two possible primary pathways to radical-pair formation that differ by three orders of magnitude in their kinetics. The fast (short-range) pathway is dominant, but the existence of an alternative slow (long-range) charge-separation pathway hints at the evolution of redundancy that may serve other purposes, adaptive or protective, related to formation of the unique oxidative species that drives water oxidation in PSII. 相似文献
308.
Maurizio Galimberti Emilio Martini Fabrizio Piemontesi Franco Sartori Isabella Camurati Luigi Resconi Enrico Albizzati 《Macromolecular Symposia》1995,89(1):259-275
In this paper, new polyolefin elastomers, obtained from metallocene based catalytic systems, are presented. The potentialities of metallocenes for the preparation of polyolefin elastomers are discussed with reference to the traditional vanadium and titanium based catalysts. The role played by a Ziegler - Natta catalyst, either stereospecific or aspecific, is discussed. 相似文献
309.
Yaowen Liu Martin C. Dietl Robin Heckershoff Chunyu Han Hongwei Shi Dr. Matthias Rudolph Dr. Frank Rominger Dr. Isabella Caligiuri Kanwal Asif Muhammad Adeel Dr. Thomas Scattolin Prof. Dr. A. Stephen K. Hashmi 《Angewandte Chemie (International ed. in English)》2023,62(34):e202304672
Due to its excellent bioactivity profile, which is increasingly utilized in pharmaceutical and synthetic chemistry, spirooxindole is an important core scaffold. We herein describe an efficient method for the construction of highly functionalized new spirooxindolocarbamates via a gold-catalyzed cycloaddition reaction of terminal alkynes or ynamides with isatin-derived ketimines. This protocol has a good functional group compatibility, uses readily available starting materials, mild reaction conditions, low catalyst loadings and no additives. It enables the transformation of various functionalized alkyne groups into cyclic carbamates. Gram-scale synthesis was achieved and DFT calculations verify the feasibility of the mechanistic proposal. Some of the target products exhibit good to excellent antiproliferative activity on human tumor cell lines. In addition, one of the most active compounds displayed a remarkable selectivity towards tumor cells over normal ones. 相似文献