Mechanism of simultaneously refolding and purification of proteins by hydrophobic interaction chromatographic unit and applications

The hydrophobic amino acid residues of a denatured protein molecule tend to react with the particles of the stationary phase of hydrophobic interaction chromatography (STHIC). These hydrophobic interactions prevent the denatured protein molecules from aggregating with each other. The STHIC can provide high enough energy to a denatured protein molecule to make it dehydration and to refold it into its native or various intermediate states. The outcome not only depends on the specific interactions between amino acids, the structure of STHIC, but also depends on the association between the STHIC and mobile phase. The mechanism of protein refolding and the principle of its quality control by HPHIC were also presented. By appropriate selection of the chromatographic condition, several denatured proteins can be refolded and separated simultaneously in a single chromatographic run. A specially designed unit, with diameter much larger than its length, was designed and employed for both laboratory and preparative     

Application of silver electrode to the electrochemical studies of hemoglobin

Several aspects of the application of silver electrode to the electrochemical studies of hemoglobin have been discussed in this paper . The silver electrode could not only be used directly as the electrode for the electrochemical studies of hemoglobin, but also react with phenothiazine and benzimidazole to give stable and useful mediator-coated electrodes. In addition, the silver electrode could help sodium dodecyl sulfate to give full play to its promoting effect on the protein.     

Promotional Effect of Bismuth as Dopant in Bi-Doped Vanadyl Pyrophosphate Catalysts for Selective Oxidation of n-Butane to Maleic Anhydride

Bismuth-promoted (1% and 3%) vanadyl pyrophosphate catalysts were prepared by refluxing Bi(NO3)3·5H2O and VOPO4·2H2O in isobutanol. The incorporation of Bi into the catalysts lattice increased the surface area and lowered the overall V oxidation state. Profiles of temperature programmed reduction (TPR) in H2 show a significant shift of the maxima of major reduction peaks to lower temperatures for the Bi-promoted catalysts. A new peak was also observed at the low temperature region for the catalyst with 3% of Bi dopant. The addition of Bi also increased the total amount of oxygen removed from the catalysts. The reduction pattern and reactivity information provide fundamental insight into the catalytic properties of the catalysts. Bi-promoted catalysts were found to be highly active (71% and 81% conversion for 1% and 3% Bi promoted catalysts, respectively, at 703 K), as compared to the unpromoted material (47% conversion). The higher activity of the Bi-promoted catalysts is due to that these catalysts possess highly active and labile lattice oxygen. The better catalytic performance can also be attributed to the larger surface area.     

Fatty Acid Composition of Tobacco Seed Oil and Synthesis of Alkyd Resin

The fatty acid composition of tobacco seed oil revealed that the oil is rich in unsaturated fatty acids, having linoleic acid （71.63%）, oleic acid （13.46%） and palmitic acid （8.72%） as the most abundant unsaturated and saturated fatty acids respectively. So the tobacco oil was characterized as semi-drying type on the basis of fatty acid composition. The synthesis of alkyd resin was carried out by alcoholysis or monoglyceride process using an alkali refined tobacco seed oil, pentaerythritol, cis-1,2,3,6-tetrahydrophthalic anhydride along with lithium hydroxide as catalyst. The alkyd resin so prepared was found to be bright and of low color with high gloss. The drying and hardness properties and adhesion of the tobacco seed oil derived alkyd resin were also found a bit superior to those of other alkyd resins of the same oil length. In addition, the water and acid resistance of the said alkyd was also found comparable to the other alkyds.     

The new approach of standardization of capillary electrophoresis

In this paper, we develope the new standardization methods to eliminate the influence in capillary electrophoresis (CE). The markers were used to determine the basis position and then correct the data of sample by the migration time of standard sample, and make the migration time of samples consistent with the standard sample by the criterion of the marker. The problem of time transition was corrected in this way. Then according to the peak height or peak area of the marker in the sample (peak height was used here) compared with the standard sample, the sample data was zoomed appropriately. The absorbance error was made to be correct. The wavelet de-noise method was also used to make the data smooth and get a good baseline.     

Calculations of heat of solvation by a simple electrostatic approach to molecular interactions

An extremely simple formula to estimate the heat of formation of complexes between anion and a polar molecule or between highly polar systems is presented.The formula is entirelyelectrostatic and the expression used is verified by means of perturbation theory.This formula is test-ed for several ion-molecule and molecule-molecule pairs.It is also applied to estimate the heat ofhydration of simple salts.     

The effects of Te on the performance of Mo-V catalysts prepared by hydrothermal synthesis

Some Mo-V-Te-La catalysts with varied component were prepared by hydrothermal synthesis and dried with microwave method. The component of the catalyst were greatly affected the crystal structure and Raman spectrum. The phase in the catalysts was different when the Mo, V, and Te content varied. When the catalyst containing the same Mo, V content, due to the effect of dopant of Te element (V0.07 Mo0.93)5O14 became the main phase in the catalyst. The catalyst also showed good activity for the reaction of selective oxidation propane to acrolein and acrylic acid.     

A New Method of Separation of Four Benzodiazepines by RP-CEC

A new method to separate diazepam, nitrazepam, estazolam, alprazolam was established on both C18 and C8 CEC columns. The influence of separation voltage, Tris concentration, column temperature and the percentage of acetonitrile on the resolution and retention behavior of four benzodiazepines was investigated. The results showed that the percentage of acetonitrile had the largest effect on the resolution and retention behavior of the four benzodiazepines. Other separation conditions had also effects on the resolution and retention behavior, but smaller than the concentration of acetonitrile. Optimum separation conditions were obtained to separate four benzodiazepines on C18 and C8 CEC columns.     

QCM Detection of Adhesion, Spreading and Proliferation of Human Breast Cancer Cells （MCF-7） on a Gold Surface

The quartz crystal microbalance (QCM) was used to monitor the one-day incubation of human breast cancer cells (MCF-7) on the gold electrode. In combination with an optical microscope simulation experiment, the cell-population pictures at various stages, the QCM responses to the cells' adhesion, spreading and proliferation on the electrode surface were discussed. The △f0 and △R1 responses were found mainly from mixed effects of viscodensity and surface stress, and in proportion to the cell coverage, rather than to the number of cells at the electrode. The significant fore-and-aft changes in cyclic voltammetry and electrochemical impedance spectroscopy of the ferri-ferrocyanide redox couple also proved that the cells were adhesion to the gold surface.     

Facile synthesis of a tricyclohexylphosphine‐stabilized η3‐allyl‐carboxylato Ni(II) complex and its relevance in electrochemical butadiene carbon dioxide coupling

With the reaction of bis(1,5‐cyclooctadiene)nickel(0) and trans‐penta‐2,4‐dienoic acid in the presence of tricyclohexylphosphine, a new more general method was developed to synthesize cyclic π³‐allyl‐carboxylato Ni(II) complexes, which are known to be intermediates in the C? C coupling of butadiene and CO₂. The cyclic π³‐allyl‐carboxylato Ni(II) complex obtained is tested as a mediator in the electrochemical coupling reaction of butadiene and carbon dioxide. We also demonstrate the dependency on the coordination sphere by using platinum instead of nickel as the metal center. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis of difluoroalkyl-γ-butyrolactones from iododifluoromethyl ketones and 4-pentenoic acids

A convenient and efficient approach for difluoroalkyl-containing γ-butyrolactones via the radical addition reaction of iododifluoromethyl ketones with 4-pentenoic acids initiated by AIBN in CH₃CN at 60 ℃ was reported. Various difluoroalkyl-containing δ-valerolactones were also synthesized under this reaction conditions.     

羟丙基-β-环糊精对1-羟基芘与牛血清白蛋白相互作用的影响

在模拟生理条件下, 利用荧光光谱、 圆二色光谱和紫外-可见吸收光谱探究了羟丙基-β-环糊精(HPCD)对1-羟基芘(1-OHPyr)与牛血清白蛋白(BSA)相互作用的影响及其相关机制. 结果表明, 291 K下HPCD可使1-OHPyr与BSA的结合常数降低为1.45×10⁵ L/mol; 导致1-OHPyr-BSA体系中BSA的α-螺旋含量恢复, 色氨酸(TRP)残基周围微环境的极性变化减弱; 致使1-OHPyr及BSA的荧光寿命均延长, 且二者的结合距离增大. 初步研究结果表明, HPCD与1-OHPyr的包络作用是HPCD影响BSA与1-OHPyr结合的主要原因.     

Acylation of Anisole Catalyzed by Hierarchical Porous Hβ Zeolite Modified with Cr

Modified hierarchical porous Hβ zeolite was obtained by metal modification of Hβ zeolite, which was treated with alkaline solution, and the catalysts before and after modification were characterized by means of X-ray diffraction(XRD), nitrogen adsorption-desorption, scanning electron microscopy(SEM), X-ray fluorescence(XRF), NH₃ temperature-programmed desorption and Fourier-transform infrared spectroscopy(FTIR). The activities of acylation of anisole with acetic anhydride were also investigated. The results show that the Hβ zeolite, which was treated with alkaline solution has microporous and mesoporous structures that could improve the diffusion performance of chemical reaction. The amount of acid was modulated with metal modification. The Hβ zeolite modified by 5%(mass fraction) metal chromium had the best catalytic performance. The conversion of acetic anhydride acylation was 93.01% under the optimal conditions, which was higher than that of other catalysts. The catalyst not only showed good activity, but also exhibited a stable performance in regeneration tests.     

“Texas-Sized” Molecular Boxes: From Chemistry to Applications

The design and synthesis of novel macrocyclic host molecules continues to attract attention because such species play important roles in supramolecular chemistry. However, the discovery of new classes of macrocycles presents a considerable challenge due to the need to embody by design effective molecular recognition features, as well as ideally the development of synthetic routes that permit further functionalization. In 2010, we reported a new class of macrocyclic hosts: a set of tetracationic imidazolium macrocycles, which we termed “Texas-sized” molecular boxes (TxSBs) in homage to Stoddart’s classic “blue box” (CBPQT⁴⁺). Compared with the rigid blue box, the first generation TxSB displayed considerably greater conformational flexibility and a relatively large central cavity, making it a good host for a variety of electron-rich guests. In this review, we provide a comprehensive summary of TxSB chemistry, detailing our recent progress in the area of anion-responsive supramolecular self-assembly and applications of the underlying chemistry to water purification, information storage, and controlled drug release. Our objective is to provide not only a review of the fundamental findings, but also to outline future research directions where TxSBs and their constructs may have a role to play.     

γ-Fe2O3纳米纤维的丙酮敏感特性

采用静电纺丝法制备了PVP/FeC₆H₅O₇复合纳米纤维, 并将复合纤维在500 ℃高温烧结3 h, X射线衍射分析(XRD)表明, 烧结后的产物为正尖晶石结构的γ-Fe₂O₃晶体. 扫描电子显微镜(SEM)观测结果表明, 制得了直径均匀、 连续的复合纳米纤维, 其平均直径约为1000 nm; 烧结后的γ-Fe₂O₃纳米纤维保持了其连续性, 但纤维发生了收缩, 直径较烧结前小, 平均约为600 nm. 比表面积分析表明, γ-Fe₂O₃纳米纤维比表面积为57.18 m²/g. 气敏性能测试结果表明, 230 ℃为γ-Fe₂O₃纳米纤维检测丙酮气体的最佳工作温度. 在此温度下, γ-Fe₂O₃纳米纤维对丙酮气体表现出高响应度[S=6.9, c(Acetone)=7.88×10⁴ mg/m³]和线性度(7.88×10²~1.58×10⁵ mg/m³浓度范围内). 同时, γ-Fe₂O₃纳米纤维气体传感器件还表现出良好的长期稳定性.     

基于β-环糊精的多肽支臂星状聚合物的制备及性能

以β-环糊精(β-CD)为起始原料, 通过磺酰化及乙二胺基取代等过程, 制备具有端氨基的中间体β-环糊精(6-en-β-CD); 再以6-en-β-CD为引发剂, 通过赖氨酸N-羧基环内酸酐(Lys-NCA)和谷氨酸N-羧基环内酸酐(Glu-NCA)的混合开环聚合(ROP)和脱苄氧羰基(Cbz)保护等反应, 制备了以β-CD为核、 混聚多肽为支臂的星状聚合物[6-聚(谷氨酸-赖氨酸)-β-CD]. 以基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)、 核磁共振波谱(NMR)和傅里叶变换红外光谱(FTIR)等对星状聚合物及中间体结构进行表征; 同时采用圆二色光谱(CD)和噻唑蓝(MTT)法对该聚合物的二级结构和体外毒性进行了考察. 结果表明, 所得星状聚合物的重均分子量(M_w)为4626, 多分散系数(PDI)为1.10, 平均聚合度(DP)为27.1; 在水溶液中星状聚合物的二级结构是无规则线团; 在5 mg/mL浓度下, 细胞存活率可达到94%以上, 没有呈现明显体外细胞毒性, 具有潜在的药用前景.     

磺丁基醚-β-环糊精修饰毛细管电色谱拆分地平类药物对映体

采用甲基丙烯酸缩水甘油酯原位聚合物基质, 将磺丁基醚-β-环糊精修饰到毛细管内壁, 制得了一种毛细管电色谱手性柱(SECDP), 并通过红外光谱(IR)和扫描电子显微镜(SEM)表征了其结构. 磺酸基可提供足够稳定的正向电渗流(EOF), 基于磺丁基醚-β-环糊精在固定相和流动相中的协同作用, 通过优化手性添加剂浓度、 pH值、 施加电压、 温度及有机调节剂含量等条件, 利用该开管电色谱柱拆分了氨氯地平、 尼莫地平和尼卡地平等10种地平类手性药物对映体. 优化的流动相组成为20 mmol/L NaH₂PO₄(pH=4.0), 含4.0 mmol/L 磺丁基醚-β-环糊精, 乙腈的体积分数为10%~25%, 施加电压15~25 kV, 温度为15 ℃, 电动进样2 kV×5 s, 检测波长为236 nm. 在上述条件下, 分离度(R_S)可达3.62, 柱效达61011块/m, 分析时间一般为6~15 min. 基于色谱分离数据, 探讨了相关的手性分离机理.     

水催化2个酯分子相互转化反应的理论研究

从印楝植物内生真菌Phomopsis sp.培养液中分离得到的4-acetoxymultiplolide(1)和1-acetoxymultiplo-lide(2)在室温及水存在下能够相互转化. 提出二者相互转化最可能的4个途径(机理A~D). 在B3LYP/6-311+G(d,p)水平进行气相条件的优化, 结果表明, 无水催化的机理A中TS1和TS2的活化能均显著大于120 kJ/mol, 2个分子水催化的机理D中TS1和TS2的活化能则显著降低. 计算结果显示水的溶剂化效应能进一步降低机理D中TS1和TS2的活化能. 在MP2/6-311++G(2d,2p)//B3LYP/6-311+G(d,p)水平计算了单点能, 得到在水相时机理D中TS1和TS2的活化能分别为106.24和107.37 kJ/mol. 因此, 机理D是化合物1 和2在室温下及水存在时相互转化最可能的途径, 该途径是一种特殊的水催化分子内酯的醇解反应, 也是一种经典的亲核加成反应, 通过一种新的叔醇中间体实现.     

Co-Opting Host Receptors for Targeted Delivery of Bioconjugates—From Drugs to Bugs

Bioconjugation has allowed scientists to combine multiple functional elements into one biological or biochemical unit. This assembly can result in the production of constructs that are targeted to a specific site or cell type in order to enhance the response to, or activity of, the conjugated moiety. In the case of cancer treatments, selectively targeting chemotherapies to the cells of interest limit harmful side effects and enhance efficacy. Targeting through conjugation is also advantageous in delivering treatments to difficult-to-reach tissues, such as the brain or infections deep in the lung. Bacterial infections can be more selectively treated by conjugating antibiotics to microbe-specific entities; helping to avoid antibiotic resistance across commensal bacterial species. In the case of vaccine development, conjugation is used to enhance efficacy without compromising safety. In this work, we will review the previously mentioned areas in which bioconjugation has created new possibilities and advanced treatments.