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Protein dimers are either homodimers (complexation of identical monomers) or heterodimers (complexation of non-identical monomers). These dimers are common in catalysis and regulation. However, the molecular principles of protein dimer interactions are difficult to understand mainly due to the geometrical and chemical characteristics of proteins. Nonetheless, the principles of protein dimer interactions are often studied using a dataset of 3D structural complexes determined by X-ray crystallography. A number of physical and chemical properties govern protein dimer interactions. Yet, a handful of such properties are known to dominate protein dimer interfaces. Here, we discuss the differences between homodimer and heterodimer interfaces using a selected set of interface properties. 相似文献
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Under hydrothermal condition, two novel organic-inorganic hybrid compounds, [Cu(bpp)][Cu2.5(bpp)3(Hbpp)]H0.5[BW12O40]·1.5H2O (1) and [Cu(en)2(H2O)]{[Cu(bpp)]3[AlW12O40]}·H2O (2) (bpp = 1,3-bis(4-pyridyl)propane; en = ethylenediamine), have been synthesized based on B/Al atom-centered Keggin-type polyoxometalates combined with Cu ions and bpp ligands. The two compounds are characterized through single-crystal X-ray diffraction analysis, elemental analyse, IR, UV and TG. For compound 1, as the nodes, the [BW12O40]5− polyanions link to the [Cu2.5(bpp)3(Hbpp)]3.5+ oligomers, leading to the formation of 1D helical chains which further attach to the macrocycles [Cu2(bpp)2]2+ via the Cu-O weak interaction to construct the 2D “wave-like” layers. For compound 2, the {[Cu(bpp)]4[AlW12O40]2} unit is obtained by the interaction between two Keggin-type [AlW12O40]5− polyanions and one tetranuclear macrocycle composed by four [Cu(bpp)]+ complex cations. Furthermore, the units are sandwiched by two 1D “wave-like” polymeric chains resulting in a new 1D structure. In addition, the electrochemical properties and electrocatalytic activities of these two compounds have been studied in this paper. 相似文献
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Song Gao Jingxiang Zhao Baibin Zhou Kai Yu Zhanhua Su Lu Wang Yongkui Yin Zhifeng Zhao Yang Yu Ying Chen 《Inorganica chimica acta》2011,379(1):151
A series of novel polytungstates, [{Cu(bim)(H2O)2}4(H4W12O42)]·14H2O 1, (Himi)6[{Mn(imi)(H2O)}(H4W12O42)]·2H2O 2, [{Cu0.5(H2O)}2{Cu0.5(H2O)2}2{Cu (bim)(H2O)2}2(H4W12O42)]·10H2O 3 and [{Na(H2O)4}2{Cu0.5(H2O)}4{Cu0.5 (H2O)1.5}2(H4W12O42)]·3H2O 4 (imi = imidazole; bim = 2,2′-biimidazole), have been obtained by the routine synthetic reactions in aqueous solution and characterized by IR, X-ray powder diffraction, UV, elemental analysis, TG and X-ray single-crystal diffraction. All the compounds contain the [H4W12O42]8− polyanions as building units. Compound 1 is isolated structure, which is modified with four {Cu(bim)(H2O)2}2+ fragments. The compound 2 exhibits an infinite 1D “wave-like” chain based on the interaction between the [H4W12O42]8− polyanion and [Mn(imi)(H2O)]2+ complex. The 2D layered structure of the compound 3 is formed by the interconnection 1D [{Cu0.5(H2O)}2(H4W12O42)]6− and [{Cu0.5(H2O)2}2(H4W12O42)]6− chains. While compound 4 can be abstracted of structural topology with (6,2)-connected 3D network. In addition, the electrochemical properties of these compounds are investigated. 相似文献
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将白地霉脂肪酶基因N端与酿酒酵母FLO絮凝结构域序列融合,构建成脂肪酶毕赤酵母表面展示载体并转化毕赤酵母GS115。免疫荧光检测证实脂肪酶已展示于毕赤酵母细胞表面。甲醇诱导96 h后展示酶活性达到81 U/g干细胞,酶的热稳定性较游离酶有较大提高,50℃孵育4 h后酶活仍保持初始酶活70%以上。 相似文献
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Rhodotorula glutinis is known to accumulate large amounts of carotenoids under certain culture conditions, which have very important industrial applications. So far, the molecular mechanism of regulating carotenogenesis is still not well understood. To better understand the carotenogenesis process, it requires methods that can detect carotenogenesis rapidly and reliably in single live cells. In this paper, a method based on laser tweezers Raman spectroscopy (LTRS) was developed to directly detect carotenoids, as well as other important biological molecules in single live R. glutinis cells. The data showed that the accumulation of carotenoids and lipids occurred mainly in the late exponential and stationary phases when the cell growth was inhibited by nutrient limitation. Meanwhile, the carotenoid concentration changed together with the concentration of nucleic acids, which increased in the first phase and decreased in the last phase of the culture. These data demonstrate that LTRS is a rapid, convenient, and reliable method to study the carotenogenesis process in vivo. 相似文献
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Solvent Engineering Boosts the Efficiency of Paintable Carbon‐Based Perovskite Solar Cells to Beyond 14% 下载免费PDF全文
Haining Chen Zhanhua Wei Hexiang He Xiaoli Zheng Kam Sing Wong Shihe Yang 《Liver Transplantation》2016,6(8)
Carbon‐based hole transport material (HTM)‐free perovskite solar cells (PSCs) have shown much promise for practical applications because of their high stability and low cost. However, the efficiencies of this kind of PSCs are still relatively low, especially for the simplest paintable carbon‐based PSCs, in comparison with the organic HTM‐based PSCs. This can be imputed to the perovskite deposition methods that are not very suitable for this kind of devices. A solvent engineering strategy based on two‐step sequential method is exploited to prepare a high‐quality perovskite layer for the paintable carbon‐based PSCs in which the solvent for CH3NH3I (MAI) solution at the second step is changed from isopropanol (IPA) to a mixed solvent of IPA/Cyclohexane (CYHEX). This mixed solvent not only accelerates the conversion of PbI2 to CH3NH3PbI3 but also suppresses the Ostwald ripening process resulting in a high‐quality perovskite layer, e.g., pure phase, even surface, and compact capping layer. The paintable carbon‐based PSCs fabricated from IPA/CYHEX solvent exhibits a considerable enhancement in photovoltaic performance and performance reproducibility in comparison with that from pure IPA, especially on fill factor (FF), owing mainly to the better contact of perovskite/carbon interface, lower trap density in perovskite, higher light absorption ability, and faster charge transport of perovskite layer. As a result, the highest power conversion efficiency (PCE) of 14.38% is obtained, which is a record value for carbon‐based HTM‐free PSCs. Furthermore, a PCE of as high as 10% is achieved for the large area device (1 cm2), also the highest of its kind. 相似文献
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A series of nanocapsules with carboxymethyl cellulose (CMC)-modified melamine-formaldehyde as the shell material and phase change paraffin as the core material were prepared by in situ polymerization. The modified capsules were examined using Fourier transform infrared spectra, scanning electronic microscope, differential scanning calorimeter, and optical microscopy, and two factors that influence paraffin emulsion preparation (emulsifier type and stirring rate) were investigated. The effects of the synthesis conditions used for the prepolymer on the surface morphology of the capsules were also studied. We found that phase change capsules prepared with both anionic and nonionic emulsifiers were superior to those prepared with a simple emulsifier. The best performance of the paraffin emulsion was obtained when the emulsion was stirred at 8,000 rpm during preparation. The optimal prepolymer reaction conditions to give smooth capsules with good dispersibility and complete morphology were reaction temperature 72.5 °C, reaction time 75 min, and pH?8.5. The CMC-modified nanocapsules have a phase change enthalpy of 83.46 J/g, are fully encased, and are uniform, with an average particle size of 50 nm. 相似文献