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951.
NMR Structure of a Triangulenium‐Based Long‐Lived Fluorescence Probe Bound to a G‐Quadruplex 下载免费PDF全文
Anita Kotar Dr. Baifan Wang Dr. Arun Shivalingam Dr. Jorge Gonzalez‐Garcia Prof. Dr. Ramon Vilar Prof. Dr. Janez Plavec 《Angewandte Chemie (International ed. in English)》2016,55(40):12508-12511
An NMR structural study of the interaction between a small‐molecule optical probe (DAOTA‐M2) and a G‐quadruplex from the promoter region of the c‐myc oncogene revealed that they interact at 1:2 binding stoichiometry. NMR‐restrained structural calculations show that binding of DAOTA‐M2 occurs mainly through π–π stacking between the polyaromatic core of the ligand and guanine residues of the outer G‐quartets. Interestingly, the binding affinities of DAOTA‐M2 differ by a factor of two for the outer G‐quartets of the unimolecular parallel G‐quadruplex under study. Unrestrained MD calculations indicate that DAOTA‐M2 displays significant dynamic behavior when stacked on a G‐quartet plane. These studies provide molecular guidelines for the design of triangulenium derivatives that can be used as optical probes for G‐quadruplexes. 相似文献
952.
[reaction: see text] A readily available chiral amino alcohol has been immobilized on silica by sol-gel synthesis and grafting. The solid prepared according to the latter method led to the best enantioselectivity (77% ee) described for the asymmetric addition of diethylzinc to benzaldehyde using inorganic solids. 相似文献
953.
Hernández-Pascacio J Garza C Banquy X Díaz-Vergara N Amigo A Ramos S Castillo R Costas M Piñeiro A 《The journal of physical chemistry. B》2007,111(44):12625-12630
Native alpha-cyclodextrin (alpha-CD) is found to spontaneously form films at aqueous solution/air interfaces. Shape-response measurements to volume perturbations on drops hanging from a capillary indicate that temperature and sodium dodecyl sulfate (SDS) concentration strongly modify the viscoelastic properties of such films. By using isothermal titration calorimetry (ITC), Brewster angle microscopy (BAM), atomic force microscopy (AFM), and molecular dynamics (MD) simulations, it is shown that the films consist of self-assembled nanotubes whose building blocks are cyclodextrin dimers (alpha-CD2) and alpha-CD2-SDS1 complexes. 相似文献
954.
Paulo Jorge Paes-Leme 《Annals of Physics》1978,115(2):367-387
The leading Ornstein-Zernike behavior of the truncated two-point function G(x) is obtained from information on the poles of the Fourier transform G~(p). Analyticity of G~(p) as a function of the complex variables p and the inverse temperature β is studied in detail for |β| sufficiently small. 相似文献
955.
We argue that recent developments in discretizations of classical and quantum gravity imply a new paradigm for doing research
in these areas. The paradigm consists in discretizing the theory in such a way that the resulting discrete theory has no constraints.
This solves many of the hard conceptual problems of quantum gravity. It also appears as a useful tool in some numerical simulations
of interest in classical relativity. We outline some of the salient aspects and results of this new framework.
Fifth Award in the 2005 Essay Competition of the Gravity Research Foundation. - Ed. 相似文献
956.
Martínez-Cuenca R Durán V Arines J Ares J Jaroszewicz Z Bará S Martínez-León L Lancis J 《Optics letters》2011,36(18):3702-3704
We propose a closed-loop adaptive optical arrangement based on a single spatial light modulator that simultaneously works as a correction unit and as the key element of a wavefront sensor. This is possible by using a liquid crystal on silicon display whose active area is divided into two halves that are respectively programmed for sensing and correction. We analyze the performance of this architecture to implement an adaptive optical system. Results showing a closed-loop operation are reported, as well as a proof of concept for dealing with aberrations comparable to those typically found in human eyes. 相似文献
957.
Endotoxins (also known as lipopolysaccharides (LPS)) are undesirable by products of recombinant proteins, purified from Escherichia coli. LPS can be considered stable under a wide range of temperature and pH, making their removal one of the most difficult tasks in downstream processes during protein purification. The inherent toxicity of LPS makes their removal an important step for the application of these proteins in several biological assays and for a safe parenteral administration. Immobilized metal affinity chromatography (IMAC) enables the affinity interactions between the metal ions (immobilized on the support through the chelating compound) and the target molecules, thus enabling high efficiency separation of the target molecules from other components present in a mixture. Affinity chromatography is applied with Ca2+ iminodiacetic acid (IDA) to remove most of the LPS contaminants from the end product (more than 90%). In this study, the adsorption of LPS on an IDA-Ca2+was investigated. The adsorption Freundlich isotherm of LPS-IDA-Ca2+provides a theoretical basis for LPS removal. It was found that LPS is bound mainly by interactions between the phosphate group in LPS and Ca2+ligands on the beads. The factors such as pH (4.0 or 5.5) and ionic strength (1.0 mol/L) are essential to obtain effective removal of LPS for contaminant levels between endotoxin’ concentration values less than 100 EU/mL and 100000 EU/mL. This new protocol represents a substantial advantage in time, effort, and production costs. 相似文献
958.
This paper studies how the behavior of a proper isometric immersion into the hyperbolic space is influenced by its behavior
at infinity. Our first result states that a proper isometric minimal immersion into the hyperbolic space with the asymptotic
boundary contained in a sphere reduces codimension. This result is a corollary of a more general one that establishes a sharp
lower bound for the sup-norm of the mean curvature vector of a Proper isometric immersion into the Hyperbolic space whose
Asymptotic boundary is contained in a sphere. We also prove that a properly immersed hypersurface with mean curvature satisfying sup
p∈Σ ||H(p)|| < 1 has no isolated points in its asymptotic boundary. Our main tool is a Tangency principle for isometric immersions of arbitrary
codimension.
This work is partially supported by CAPES, Brazil. 相似文献
959.
960.
We reconsider the unified model of gravitation and Yang–Mills interactions proposed by Chakraborty and Peldán, in the light of recent formal developments in loop quantum gravity. In particular, we show that one can promote the Hamiltonian constraint of the unified model to a well defined anomaly-free quantum operator using the techniques introduced by Thiemann, at least for the Euclidean theory. The Lorentzian version of the model can be consistently constructed, but at the moment appears to yield a correct weak field theory only under restrictive assumptions, and its quantization appears problematic. 相似文献