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961.
Back Cover: Multifunctional Tricarbazolo Triazolophane Macrocycles: One‐Pot Preparation,Anion Binding,and Hierarchical Self‐Organization of Multilayers (Chem. Eur. J. 2/2016) 下载免费PDF全文
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Cover Picture: Sequential Anion and Cation Exchange Reactions for Complete Material Transformations of Nanoparticles with Morphological Retention (Angew. Chem. Int. Ed. 30/2015) 下载免费PDF全文
963.
CaII Binding Regulates and Dominates the Reactivity of a Transition‐Metal‐Ion‐Dependent Diesterase from Mycobacterium tuberculosis 下载免费PDF全文
Dr. Marcelo M. Pedroso Prof. James A. Larrabee Dr. Fernanda Ely Shuhui E. Gwee Dr. Nataša Mitić Prof. David L. Ollis Prof. Lawrence R. Gahan Prof. Gerhard Schenk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(3):999-1009
The diesterase Rv0805 from Mycobacterium tuberculosis is a dinuclear metallohydrolase that plays an important role in signal transduction by controlling the intracellular levels of cyclic nucleotides. As Rv0805 is essential for mycobacterial growth it is a promising new target for the development of chemotherapeutics to treat tuberculosis. The in vivo metal‐ion composition of Rv0805 is subject to debate. Here, we demonstrate that the active site accommodates two divalent transition metal ions with binding affinities ranging from approximately 50 nm for MnII to about 600 nm for ZnII. In contrast, the enzyme GpdQ from Enterobacter aerogenes, despite having a coordination sphere identical to that of Rv0805, binds only one metal ion in the absence of substrate, thus demonstrating the significance of the outer sphere to modulate metal‐ion binding and enzymatic reactivity. CaII also binds tightly to Rv0805 (Kd≈40 nm ), but kinetic, calorimetric, and spectroscopic data indicate that two CaII ions bind at a site different from the dinuclear transition‐metal‐ion binding site. CaII acts as an activator of the enzymatic activity but is able to promote the hydrolysis of substrates even in the absence of transition‐metal ions, thus providing an effective strategy for the regulation of the enzymatic activity. 相似文献
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Dimitrios A. Lamprou James R. Smith Thomas G. Nevell Eugen Barbu Corinne Stone Colin R. Willis Richard J. Ewen John Tsibouklis 《Surface science》2010,604(5-6):541-547
Self-assembled structures of alkanethiols that have been deposited on gold from ethanolic solutions are susceptible to both chemical and physical changes: ethanol provides a medium for the formation of S-alkyl hydrogen thiocarbonates and related compounds via reaction with dissolved, atmospheric, CO2. Deposition from ethanolic solutions results in multilayered structures incorporating these compounds, which at room temperature are susceptible to time-dependent structural rearrangement and molecular migration. 相似文献
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A. Hossain A.E. Bolotnikov G.S. Camarda Y. Cui G. Yang K-H. Kim R. Gul L. Xu R.B. James 《Journal of Crystal Growth》2010,312(11):1795-1799
We explored some unique defects in a batch of cadmium zinc telluride (CdZnTe) crystals, along with dislocations and Te-rich decorated features, revealed by chemical etching. We extensively investigated these distinctive imperfections in the crystals to identify their origin, dimensions, and distribution in the bulk material. We estimated that these features ranged from 50 to 500 μm in diameter, and their depth was about ∼300 μm. The density of these features ranged between 2×102 and 1×103 per cm3. We elaborated a model of them and projected their effect on charge collection and spectral response. In addition, we fabricated detectors with these defective crystals and acquired fine details of charge-transport phenomena over the detectors’ volume using a high-spatial resolution (25 μm) X-ray response mapping technique. We related the results to better understand the defects and their influence on the charge-transport properties of the devices. The role of the defects was identified by correlating their signatures with the findings from our theoretical model and our experimental data. 相似文献
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Baoyong Zhang James Lam Shengyuan Xu Zhan Shu 《Nonlinear Analysis: Real World Applications》2010,11(3):1963-1976
This paper is concerned with the problem of absolute exponential stability analysis for a class of continuous-time systems with sector-bounded nonlinearities and interval time-varying delays. Absolute exponential stability criteria, which depend not only on the delay range but also on the decay rate, are derived by using a novel Lyapunov functional. These criteria are expressed in the form of linear matrix inequalities (LMIs) and they can easily be checked. By solving these LMIs, estimates of the exponential decay rate and decay coefficient are obtained. A numerical example is provided to demonstrate the effectiveness of the proposed method. 相似文献
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