Competing binding of metal ions with protein studied by microdialysis

A method has been established to study the competing binding of metal ions with protein by a combined technique of microdialysis with high performance liquid chromatography (HPLC). Ni2+, Cd2+, Zn2+, Cu2+ and human serum albumin (HSA) were chosen as model metal ions and protein. The experimental results show that Ni2+ and Cu2+ share a common primary binding site on HSA, and Zn2+ and Cd2+ share a different common primary binding site from them, but there is a common multi-metal binding site for all of those four metal ions. This method show advantages of fast sampling, easily to be operated and especially to be useful when ideal spectroscopic probes are not available for the study of interaction between protein and metal ions.

Synthesis and Metal-ion Binding Properties of New N2S4O2- and N2S5O2-Donor Macrocycles

Synthetic procedures for new mixed-donor macrocycle compounds were reported. The macrocyclic compounds were used in solvent extraction metal picrates such as Ag+, Hg2+, Cd2+, Zn2+, Cu2+, Ni2+, Mn2+, Pb2+, and Co2+. The metal picrate extractions were investigated at 25±0.1°C with the aid of UV-visible spectrometry. It was found that 6,7,9,10,12,13,23,24-octahydro-19H,26Hdibenzo[h,t](1,4,7,13,16,22,10,19) dioxatetrathiadiazasiclotetracosine-20,27(21H,28H)-dione showed selectivity towards Ag+, Hg2+, and Cd2+ among the other metals. The extraction constants (Log Kex) and complex compositions were determined for the Ag+ and Hg2+ complexes for this compound and 9,10,12,13,23,24,26,27,29,30-decahydro-5H,15H-dibenzo-[h,w][1,4,7,13,16,19,25-,10,22] dioxapentathiadiazacycloheptacosine-6,16(7H,17H)-dione.

基于过程Agent的人力资源调度方法

为了根据人力资源及项目信息进行资源调度,基于过程Agent的人力资源调度方法通过对软件过程中的人力资源建模,描述和定义了任务(目标)及联合体投标模型,并根据用户对目标的偏好生成调度计划,能够为软件企业在人力资源优化调度、项目进度安排等方面提供决策支持,进而提高软件企业的项目管理能力和资源利用效率。最后通过一个实例表明了该方法的可行性和有效性。

数据驱动的多Agent装备器材保障决策支持系统

为提高复杂网络环境和任务需求下器材保障的智能化水平,提出了一个数据驱动的多Agent器材保障决策支持系统DSS(decision support system),系统中的数据、模型以及Agent可分布在不同的网络节点上,高层Agent可由粒度更小的子Agent或Agent部件组合而成;系统中的各类智能Agent相互协作,共同完成异构数据集成、多维数据集构造、器材保障模型挖掘、复杂规划问题求解,以及保障方案自动生成等任务,从而有效降低了系统开发的难度,提高了Agent协作的灵活性。研究结果表明,该系统架构能够显著提升器材保障决策方案的质量和效率。

A strategy for synthesis of ion-bonded amphiphilic miktoarm star copolymers via supramolecular macro-RAFT agent

Amphiphilic supramolecular miktoarm star copolymers linked by ionic bonds with controlled molecular weight and low polydispersity have been successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization using an ion-bonded macromolecular RAFT agent (macro-RAFT agent). Firstly, a new tetrafunctional initiator, dimethyl 4,6-bis(bromomethyl)-isophthalate, was synthesized and used as an initiator for atom transfer radical polymerization (ATRP) of styrene to form polystyrene (PSt) containing two ester groups at the middle of polymer chain. Then, the ester groups were converted into tertiary amino groups and the ion-bonded supramolecular macro-RAFT agent was obtained through the interaction between the tertiary amino group and 2-dodecylsulfanylthiocarbonylsulfanyl-2-methyl propionic acid (DMP). Finally, ion-bonded amphiphilic miktoarm star copolymer, (PSt)(2)-poly(N-isopropyl-acrylamide)(2), was prepared by RAFT polymerization of N-isopropylacrylamide (NIPAM) in the presence of the supramolecular macro-RAFT agent. The polymerization kinetics was investigated and the molecular weight and the architecture of the resulting star polymers were characterized by means of H-1-NMR, FTIR, and GPC techniques. (c) 2008 Wiley Periodicals, Inc.

Effect of the nucleating agent 1,3 : 2,4-di(3,4-dimethylbenzylidene) sorbitol on the gamma phase content of propylene/ethylene copolymer

The influence of the concentration of a nucleating agent (NA), namely 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol (DMDBS), on the gamma phase content in a propylene/ethylene copolymer was investigated by means of Differential Scanning Calorimetry (DSC), Wide-Angle X-ray Diffraction (WAXD), Small- Angle X-ray Scatter (SAXS) and Polarized Optical Microscopy (POM).

An effective method for enhancing metal-ions' selectivity of ionic liquid-based extraction system: Adding water-soluble complexing agent

Selective extraction-separation of yttrium(Ill) from heavy lanthanides into 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim][PF6]) containing Cyanex 923 was achieved by adding a water-soluble complexing agent (EDTA) to aqueous phase. The simple and environmentally benign complexing method was proved to be an effective strategy for enhancing the selectivity of [C(n)mim] [PF6]/[Tf2N]-based extraction system without increasing the loss of [C(n)mim](+). (c) 2007 Elsevier B.V. All rights reserved.

Evaluation of flavonoids binding to DNA duplexes by electrospray ionization mass spectrometry

In this study, electrospray ionization mass spectrometry (ESI-MS) was used to investigate the binding interactions of ten flavonoid aglycones and ten flavonoid glycosides with DNA duplexes. Relative binding affinities of the flavonoids toward DNA duplexes were estimated based on the fraction of bound DNA. The results revealed that the 4'-OH group of flavonoid aglycones was essential for their DNA-binding properties. Flavonoid glycosides with sugar chain linked on ring A or ring B showed enhanced binding toward the duplexes over their aglycone counterparts, whereas glycosylation of the flavonol quercetin on ring C exhibited a less pronounced effect.

Studies on alkaloids binding to GC-rich human survivin promoter DNA using positive and negative ion electrospray ionization mass spectrometry

Electrospray ionization mass spectrometry (ESI-MS) was used to investigate the binding of 13 alkaloids to two GC-rich DNA duplexes which are critical sequences in human survivin promoter. Negative ion ESI-MS was first applied to screen the binding of the alkaloids to the duplexes. Six alkaloids (including berberine, jatrorrhizine, palmatine, reserpine, berbamine, and tetrandrine) show complexation with the target DNA sequences. Relative binding affinities were estimated from the negative ion ESI data, and the alkaloids show a binding preference to the duplex with higher GC content. Positive ion ESI mass spectra of the complexes were also recorded and compared with those obtained in negative ion mode.

Microarray-Based Study of Carbohydrate-Protein Binding by Gold Nanoparticle Probes

In order to develop a novel high-throughput tool for monitoring carbohydrate-protein interactions, we prepared carbohydrate or glycoprotein microarrays by immobilizing amino modified carbohydrates on aldehyde-derivatized glass slides or glycoprotein on epoxide-derivatized glass slides and carried out lectin binding experiments by using these microarrays, respectively. The interaction events are marked by attachment of gold nanoparticles followed by silver deposition for signal enhancement. The attachment of the gold nanoparticles is achieved by standard avidin-biotin chemistry.

Self-assembly of single-stranded RNA on carbon nanotube: Polyadenylic acid to form a duplex structure

All messenger-RNA (mRNA) molecules in eukaryotic cells have a polyadenylic acid [poly (rA)] tail at the 3'-end and human poly (rA) polymerase (PAP) has been considered as a tumor-specific target. A ligand that is capable of recognizing and binding to the poly(M) tail of mRNA might interfere with the full processing of mRNA by PAP and can be a potential therapeutic agent. We report here for the first time that single-walled carbon nanotubes (SWNTs) can cause single-stranded poly (M) to self-structure and form a duplex structure, which is studied by UV melting, atomic force microscopy, circular dichroism spectroscopy, and NMR spectrometry.

Single-walled carbon nanotubes binding to human telomeric i-motif DNA under molecular-crowding conditions: More water molecules released

The natural occurrence of the human telomeric G-quadruplex or i-motif in vivo has not been demonstrated and the biological effects of the induction of these structures need to be clarified. Intracellular environments are highly crowded with various biomolecules and in vitro studies under molecular-crowding conditions will provide important information on how biomolecules behave in cells. Here we report that cell-mimic crowding can increase i-motif stability at acid pH and cause dehydration.

Amphiphilic Core-Shell Nanocarriers Based On Hyperbranched Poly(ester amide)-star-PCL: Synthesis, Characterization, and Potential as Efficient Phase Transfer Agent

Amphiphilic biodegradable star-shaped polymer was conveniently prepared by the Sn(Oct)(2)-catalyzed ring opening polymerization of c-caprolactone (CL) with hyperbranched poly(ester amide) (PEA) as a macroinitiator. Various monomer/initiator ratios were employed to vary the length of the PCL arms. H-1 NMR and FTIR characterizations showed the successful synthesis of star polymer with high initiation efficiency. SEC analysis using triple detectors, RI, light scattering, and viscosity confirmed the controlled manner of polymerization and the star architecture.