槲皮素与酪蛋白和牛血清白蛋白的相互作用及共存碳纳米管的影响

采用荧光猝灭和同步荧光法,研究了磷酸缓冲溶液(PBS, pH=7.4)中有无碳纳米管(CNTs)共存时,荧光活性物质槲皮素(Qct)与牛血清白蛋白(BSA)和酪蛋白(Cas)的相互作用. 推导了方法1(固定蛋白质浓度, 改变Qct浓度, 测量蛋白质荧光改变)和方法2(固定Qct浓度, 改变蛋白质浓度, 测量Qct荧光改变)研究分子间作用的一般方程, 由非线性最小二乘拟合法测算了结合常数K和摩尔结合比n, 并藉此定量评估了“光内滤所致猝灭”效应的影响. 研究了共存CNTs或Qct对BSA或Cas的荧光猝灭效应, 及CNTs对Qct-BSA和Qct-Cas相互作用的影响. 以同步荧光法考察了CNTs或Qct对BSA或Cas构象的影响, 并测算了CNTs或Qct与蛋白质中酪氨酸(Tyr)或色氨酸(Trp)残基相关的K和n. 结果表明, CNTs主要与处于蛋白质分子表面附近的Trp残基作用, 而小分子Qct则还可与处于蛋白质分子内部的Tyr残基作用.     

锌离子对缓冲液中槲皮素和牛血清白蛋白相互作用的影响

采用荧光光谱法和紫外光谱法研究了Zn2+离子对槲皮素(Qct)和牛血清白蛋白(BSA)在pH=7.4的Tris-HCl缓冲溶液中相互作用的影响;根据荧光猝灭双倒数图计算了Qct和BSA之间的结合常数和结合位点数.结果表明,Qct和Zn2+离子都可以使BSA的荧光强度发生猝灭;Qct和BSA之间的结合常数为3.17×107L.mol-1.s-1,结合位点数为1.32.定量计算表明,加入Zn2+离子后,Qct与BSA间的结合常数显著降低、结合位点数减小,表明Zn2+离子参与了Qct与BSA的结合过程.     

吡虫啉与牛血红蛋白相互作用的光谱研究

利用紫外可见光谱和荧光光谱研究了在生理pH值条件下农药吡虫啉与牛血红蛋白(BHb)的相互作用。实验结果表明:吡虫啉分子与BHb发生反应生成复合物,导致BHb内源荧光的猝灭,该猝灭属于静态猝灭。测定了不同温度下该反应的表观结合常数、结合位点数及结合热力学参数,热力学参数的变化表明上述作用过程是一个熵增加、自由能降低的自发分子间作用过程,吡虫啉与BHb之间以静电和疏水作用力为主;并用同步荧光光谱法探讨了吡虫啉对BHb构象的影响。     

汞(II)与牛血红蛋白相互作用的研究

本文采用紫外光谱(UV/VIS)、荧光光谱和圆二色谱等方法,对汞(II)与牛血红蛋白(BHb)的相互作用进行了研究。结果表明:Hg2 处理导致BHb紫外吸收的增加,出现LMCT带,并随Hg2 浓度的增加LMCT带强度显著增强。BHb分子中Soret带的吸收随着Hg2 作用时间的增加而持续降低,表明Hg2 使部分血红素辅基从BHb中脱离出来。蛋白内源荧光光谱显示,Hg2 与BHb的结合会影响蛋白质的三级结构和四级结构。远紫外圆二色谱表明,Hg2 处理会导致BHb蛋白的α-螺旋含量减少。     

汞(Ⅱ)与牛血红蛋白相互作用的研究

本文采用紫外光谱(UV/VIS)、荧光光谱和圆二色谱等方法,对汞(Ⅱ)与牛血红蛋白(BHb)的相互作用进行了研究.结果表明:Hg2 处理导致BHb紫外吸收的增加,出现LMCT带,并随Hg2 浓度的增加LMCT带强度显著增强.BHb分子中Soret带的吸收随着Hg2 作用时间的增加而持续降低,表明Hg2 使部分血红素辅基从BHb中脱离出来.蛋白内源荧光光谱显示,Hg2 与BHb的结合会影响蛋白质的三级结构和四级结构.远紫外圆二色谱表明,Hg2 处理会导致BHb蛋白的α-螺旋含量减少.     

分子光谱法研究铝酞菁与牛血红蛋白的相互作用

利用紫外可见吸收光谱和荧光光谱研究了在生理pH条件下铝酞菁与牛血红蛋白(BHb)的相互作用.实验结果表明:铝酞菁分子与BHb发生反应生成基态复合物,导致BHb内源荧光的猝灭,该猝灭属于静态猝灭.测定了不同温度下该反应的表观结合常数、结合位点数及结合热力学参数,热力学参数的变化表明铝酞菁与BHb之间以静电和疏水作用力为主;根据Frster能量转移理论,测得供体与受体间结合距离r和能量转移效率E;并用同步荧光光谱法探讨了铝酞菁对BHb构象的影响.     

孔雀石绿与牛血清白蛋白作用的光谱研究

应用荧光及紫外光谱法研究了孔雀石绿(MG)与牛血清白蛋白(BSA)相互作用的光谱特性。测定了16℃、26℃、36℃三个温度下的结合常数KA(7.066×103、4.638×103、1.338×103)和结合位点数n(1.2、1.1、1.0)。结果表明:MG对BSA内源荧光的猝灭机理主要为静态猝灭;MG主要以范德华力与BSA相互作用;同步荧光技术研究了MG对BSA构象的影响,表明BSA的荧光主要源于色氨酸残基,MG对BSA的构象有影响;利用F ster偶极-偶极非辐射能量转移理论,计算了三个温度下MG与BSA的作用距离(r16℃=3.30,r26℃=3.314,r36℃=3.58nm),表明MG对BSA的荧光猝灭中存在能量转移。     

光谱法研究铬(Ⅵ)与血红蛋白的相互作用

运用荧光光谱、紫外光谱、CD光谱法研究了K₂Cr₂O₇与牛血红蛋白(BHb)的相互作用。紫外光谱表明,加入铬(Ⅵ)酸根离子后,BHb分子中Soret带的吸收持续降低, 峰位红移,说明铬(Ⅵ)酸根离子可能使部分血红素辅基从BHb的空腔中脱离出来,部分转变为高铁血红蛋白。荧光光谱表明,铬(Ⅵ)酸根离子与BHb形成基态复合物导致BHb内源荧光猝灭,猝灭机理主要为静态猝灭。测定了不同温度下该反应的热力学参数,表明上述作用过程是一个熵增加、自由能降低的自发分子间作用过程,铬(Ⅵ)酸根离子与BHb之间以氢键和范徳华力相互作用为主;并用同步荧光和CD光谱技术考察了铬(Ⅵ)对BHb结构的影响。     

单宁酸与牛血红蛋白相互作用的光谱研究

利用荧光光谱技术研究了单宁酸与牛血红蛋白分子的相互作用。实验结果表明:单宁酸分子与BHb发生反应生成基态复合物,导致BHb内源荧光的猝灭,该猝灭属于静态猝灭。测定了不同温度下该反应的表观结合常数、结合位点数及结合热力学参数,热力学参数的变化表明上述作用过程是一个熵增加、自由能降低的自发分子间作用过程,单宁酸与BHb之间以疏水和氢键作用力为主;根据Frster能量转移理论,测得供体与受体间结合距离r和能量转移效率E;并用同步荧光光谱法探讨了单宁酸对BHb构象的影响。     

丁咯地尔与人血清白蛋白结合的光谱学研究

用紫外吸收光谱法、荧光光谱法和傅立叶变换红外光谱法探讨了在模拟人体生理条件下,丁咯地尔与人血清白蛋白(HSA)的结合模式.结果表明:丁咯地尔对HSA的内源荧光有显著的猝灭作用,且猝灭机理主要为静态猝灭.丁咯地尔与HSA形成了1 ∶ 1的复合物,结合常数K=7.43×102 L·mol-1(308 K).根据Fster偶极-偶极非辐射能量转移机理,求得丁咯地尔与HSA间的结合距离r=2.64 nm.由热力学参数确定其作用力以氢键和范德华力为主.同步荧光和傅立叶变换红外光谱表明丁咯地尔对HSA二级结构的含量产生影响,使HSA的α-螺旋结构的含量明显降低,β-折叠和β-转角结构的含量增加.     

Non-Hydroxamate Zinc-Binding Groups as Warheads for Histone Deacetylases

Histone deacetylases (HDACs) remove acetyl groups from acetylated lysine residues and have a large variety of substrates and interaction partners. Therefore, it is not surprising that HDACs are involved in many diseases. Most inhibitors of zinc-dependent HDACs (HDACis) including approved drugs contain a hydroxamate as a zinc-binding group (ZBG), which is by far the biggest contributor to affinity, while chemical variation of the residual molecule is exploited to create more or less selectivity against HDAC isozymes or other metalloproteins. Hydroxamates have a propensity for nonspecificity and have recently come under considerable suspicion because of potential mutagenicity. Therefore, there are significant concerns when applying hydroxamate-containing compounds as therapeutics in chronic diseases beyond oncology due to unwanted toxic side effects. In the last years, several alternative ZBGs have been developed, which can replace the critical hydroxamate group in HDACis, while preserving high potency. Moreover, these compounds can be developed into highly selective inhibitors. This review aims at providing an overview of the progress in the field of non-hydroxamic HDACis in the time period from 2015 to present. Formally, ZBGs are clustered according to their binding mode and structural similarity to provide qualitative assessments and predictions based on available structural information.     

纳米LDH作为热稳定剂在PMMA中的应用

水滑石;;聚甲基丙烯酸甲酯;热稳定性;纳米LDH作为热稳定剂在PMMA中的应用     

Gels from a semifluorinated n-alkane in fluorinated solvents as a probe for intermolecular interactions

Diblock semifluorinated n-alkanes can form aggregates and gels in fluorinated solvents. We have investigated the thermal behavior of binary mixtures comprising F(CF₂)₈(CH₂)₁₆H and fluorinated solvents. The solvents were perfluorohexane, perfluoroheptane, perfluorooctane, perfluorooctyl bromide, perfluorodecalin, and perfluorotributylamine. The phase diagrams were used to calculate the activity coefficients of the two components and the main excess thermodynamic functions. The solubility and self-assembly behavior of F₈H₁₆ in the fluorinated solvents are related to the different solute–solvent dispersion interactions that depend on the polarizabilities and ionization potentials of the interacting species, and on the structural properties of the solvent.     

Mixed Ligand Complexes of Palladium (II) with Diethylenetriamine as Primary Ligand and Peptides as Secondary Ligand

Solution equilibria of the system palladium (II)-diethylenetriamine (dien) and peptides have been studied. The pH-metric titration of the reaction mixture containing equimolar solutions of palladium (II), dien and peptide have shown the formation of 1:1:1 mixed ligand complex. The pK_e of the peptides studied and formation constants of the resulting complexes have been determined at 25°C. The mode of chelation has been deduced from the conductivity measurements.     

CS/TPP纳米微胶囊的制备及其载药性能

利用离子凝胶法, 以三聚磷酸钠(TPP)为交联剂, 由壳聚糖(CS)制备了CS/TPP纳米微胶囊. 用红外光谱仪、扫描电镜和粒径分析仪进行了表征, 并以牛血清蛋白(BSA)作为模型药物, 考察了所制备的CS/TPP纳米微胶囊的包载和缓释性能. 结果表明, CS/TPP纳米微胶囊的红外光谱相对于CS和TPP的红外光谱发生了很大变化, 说明CS和TPP通过正负电荷吸引聚合成囊; 粒径分析表明, 离子凝胶法可以得到粒径约430 nm的均匀分散的壳聚糖纳米微胶囊, 经冷冻干燥后粒径变为300 nm左右; 微胶囊包封率最高可达79.74%, 模型药物的持续释放时间可达7 d以上.     

Studies on the Formation of Catalytically Active PGM Nanoparticles from Model Solutions as a Basis for the Recycling of Spent Catalysts

The paper presents basic studies on the precipitation of platinum, palladium, rhodium, and ruthenium nanoparticles from model acidic solutions using sodium borohydride, ascorbic acid, and sodium formate as reducing agents and polyvinylpyrrolidone as a stabilizing agent. The size of the obtained PGM particles after precipitation with NaBH₄ solution does not exceed 55 nm. NaBH₄ is an efficient reducer; the precipitation yields for Pt, Pd, Ru, Rh are 75, 90, 65 and 85%, respectively. By precipitation with ascorbic acid, it is possible to efficiently separate Pt, Rh, and Ru from Pd from the two-component mixtures. The obtained Pt, Pd, and Rh precipitates have the catalytic ability of the catalytic reaction of p-nitrophenol to p-aminophenol. The morphological characteristic of the PGM precipitates was analyzed by AFM, SEM-EDS, and TEM.     

Synthesis of hexadecylamine capped CdS nanoparticles using heterocyclic cadmium dithiocarbamates as single source precursors

Heterocyclic cadmium dithiocarbamates, [Cd(S₂CNC₅H₁₀)₂] and [Cd(S₂CNC₉H₁₀)₂] were synthesized. The complexes were thermolysed in hexadecylamine (HDA) to give HDA capped CdS nanoparticles. A combination of close to spherical, rod, bipods and tripods was obtained by varying the reaction parameters such as precursor concentration and temperature. The optical properties and X-ray diffraction studies of the particles are also reported.     

The Future of Gas to Liquids as a Gas Monetisation Option

The paper introduces gas to liquids (GTL) as a monetising option from a technology, marketingand project perspective. GTL is complementary to LNG and pipelines. At the same time, using naturalgas as a source for fuels in the form of GTL helps countries around the world to diversify their energysupplies. Furthermore, gas-based products are inherently cleaner than oil products. Shell‘s proprietary GTL technology or SMDS (Shell Middle Distillates Synthesis), is discussed in some detail. The paperalso covers the challenges for successful implementation of GTL projects and why Shell is well positionedto take a lead in the industry on the basis of its long standing and broad experience in GTL research,plant operations, marketing and excellent track record in mega projects in the last thirty years. Shell‘scommitment to GTL is best demonstrated by the recent signing of a Heads of Agreement with Qatar Petroleum for the construction of the world‘s largest GTL plant. A key success factor is Shell‘s experiencewith marketing quantities of high quality GTL products from its 12,500 barrels per day plant at Bintulu,Malaysia since 1993. Further marketing opportunities will arise when new GTL capacity comes on-streamin the middle east when more quantities will become available to bulk users. Amongst the most interesting market will be automotive transportation, where clean GTL fuels can be positioned as an ‘alternativefuel beyond oil‘ providing energy security to host countries. Shell is actively engaging with a numberof regulators, automotive companies and governments worldwide including China, to demonstrate theperformance of GTL and its cost effectiveness in reducing local emissions. An added benefit is that GTLcan use existing infrastructure and requires no investment. Finally, the paper briefly discusses the coal toliquids (CTL) process as an alternative route to produce high quality GTL products and the key issuesrelating to the process.     

Inhibitors of biotin biosynthesis as potential herbicides

Isosteric derivatives and analogues of the 7-keto-8-aminopelargonic acid (KAPA), 7,8-diaminopelargonic acid (DAPA) and desthiobiotin (DTB) vitamer intermediates involved in the biosynthetic pathway of biotin were prepared and evaluated as potential herbicides. The most active compound was desmethyl-KAPA which displayed a GR₅₀ (concentration of the active compound that causes a 50% growth inhibition) value of 8 ppm, where values <50 ppm are considered herbicidal. Other KAPA analogs where the terminal Me group was replaced by bulkier substituents such as Et, i-Pr and HOCH₂ showed moderate activity.     

Application of water as a solvent in microwave-assisted extraction for analysis of PCBs and CBzs in fly ash

Polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs) are two classes of dioxin precursors formed in municipal solid waste incinerators (MSWIs); they produce negative health effects similar to those of dioxins. Reducing the analytical time required for determining the concentrations of these compounds in MSWIs is important for quickly evaluating their importance and assessing associated health risks. In the present study, water is used as a safe and environmentally friendly solvent in microwave-assisted extraction (MAE) for PCB and CBz analyses. MAE is compared with traditional Soxhlet extraction (SE) to determine the extraction efficiencies. The evaluation of extraction efficiencies shows that MAE has a high extraction efficiency compared with that of SE when water content is lower than 60%. Furthermore, the extraction time and organic solvent consumption are reduced with MAE compared with SE.