Nanoscale tools to selectively destroy cancer cells

We present experimental data that demonstrate the potential of synthetic crown ether modified peptide nanostructures to act as selective and efficient chemotherapeutic agents that operate by attacking and destroying cell membranes.     

Chemical tools from biology-oriented synthesis

Lessmann et al. present a chiral natural-product-derived library of alpha,beta-unsaturated delta-lactones obtained through stereoselective synthesis on a solid support [1]. Phenotypic screening of this compound collection provided new modulators of cell cycle progression and of viral cell entry with high hit rates.     

Chemical tools for functional studies of glycans

In recent years a variety of chemical approaches have been developed for elucidating the molecular basis of biological processes in which glycans participate. The chemical technologies uncovered have greatly influenced the progress of glycomics research programs. This tutorial review highlights recent advances in chemical tools which have been developed and their applications in studies aimed at gaining a better understanding of the roles that glycans play in biological processes.     

中药地榆的化学成分分析

报道了中药地榆提取物化学成分的分析.首先采用正反相硅胶色谱柱层析共分离纯化出15个单体,然后经波谱分析等方法鉴定了其中13个化合物的结构.     

Chemical databases evaluated by order theoretical tools

Data on environmental chemicals are urgently needed to comply with the future chemicals policy in the European Union. The availability of data on parameters and chemicals can be evaluated by chemometrical and environmetrical methods. Different mathematical and statistical methods are taken into account in this paper. The emphasis is set on a new, discrete mathematical method called METEOR (method of evaluation by order theory). Application of the Hasse diagram technique (HDT) of the complete data-matrix comprising 12 objects (databases) × 27 attributes (parameters + chemicals) reveals that ECOTOX (ECO), environmental fate database (EFD) and extoxnet (EXT)—also called multi-database databases—are best. Most single databases which are specialised are found in a minimal position in the Hasse diagram; these are biocatalysis/biodegradation database (BID), pesticide database (PES) and UmweltInfo (UMW). The aggregation of environmental parameters and chemicals (equal weight) leads to a slimmer data-matrix on the attribute side. However, no significant differences are found in the best and worst objects. The whole approach indicates a rather bad situation in terms of the availability of data on existing chemicals and hence an alarming signal concerning the new and existing chemicals policies of the EEC.Electronic Supplementary Material Supplementary material is available for this article at     

Chemical components of the Ephedra major from Iran

Ephedra is a dioecious shrub that belongs to the Ephedraceae family of gymnosperms. Almost all commercial applications of Ephedra extracts are derived from the ephedrine alkaloids found in the evergreen stems. The purpose of this study was to compare chemical components (total alkaloid, ephedrine, total phenol, total flavonoid and tannin) of Ephedra major plants during May to October months. The seeds and stems were collected from Bojnoord altitudes in east of Iran. Total alkaloid was separated by solvent and soxhelet extraction method. The results revealed that solvent extraction method is more efficient than soxhelet extraction method. The measurement of chemical components showed significant difference during May to October months. Data from HPLC analysis revealed that while root is depleted of ephedrine, the ephedrine amount in stem organ ranged from 1.50 ± 0.15 to 2.12 ± 0.01 mg/g dry weight. The results indicate that E. major can be as a suitable source of ephedrine.     

Chemical inhibitors: the challenge of finding the right target

A paper in this issue of Chemistry & Biology shows that the diaryl oxazole compound UA62784 that targets pancreatic cancer cells interacts with tubulin near the colchicine binding site (Tcherniuk et?al., 2011). These findings differ from previous observations, highlighting the challenges of identifying the biological target for chemical inhibitors.     

Chemical tools for E3 ubiquitin ligase study

E3 ubiquitin ligases catalyze the final step of ubiquitylation, a crucial post-translational modification involved in almost every process in eukaryotic cells. E3 ubiquitin ligases are key regulators of cellular events, and the investigation into their functions and functioning mechanisms are research areas with great importance. Synthetic or semi-synthetic tools have greatly facilitated the research about the enzyme activity, distribution in different physiological events, and catalytic mechanism of E3 ubiquitin ligase. In this review, we summarize the development of chemical tools for E3 ubiquitin ligases with an emphasis on the synthetic routes. We show the utility of these chemical tools by briefly discussing their applications in biological research.     

Chemical cross-linking and mass spectrometry as structure determination tools

Chemical cross-linking is becoming a valuable tool for the high-order structure determination of proteins and protein complexes. Cross-linking methodology is able to provide low-resolution structures when at least something is known already about the proteins under investigation. The suitability of top-down and bottom-up methodologies is discussed and further potential applications of chemical cross-linking of proteins, as well as combinations with other techniques such as hydrogen/deuterium exchange and molecular modeling, are suggested.     

Chemical tools for study and modulation of biomolecular phase transitions

Biomolecular phase transitions play an important role in organizing cellular processes in space and time. Methods and tools for studying these transitions, and the intrinsically disordered proteins (IDPs) that often drive them, are typically less developed than tools for studying their folded protein counterparts. In this perspective, we assess the current landscape of chemical tools for studying IDPs, with a specific focus on protein liquid–liquid phase separation (LLPS). We highlight methodologies that enable imaging and spectroscopic studies of these systems, including site-specific labeling with small molecules and the diverse range of capabilities offered by inteins and protein semisynthesis. We discuss strategies for introducing post-translational modifications that are central to IDP and LLPS function and regulation. We also investigate the nascent field of noncovalent small-molecule modulators of LLPS. We hope that this review of the state-of-the-art in chemical tools for interrogating IDPs and LLPS, along with an associated perspective on areas of unmet need, can serve as a valuable and timely resource for these rapidly expanding fields of study.

Chemical tools provide the ability to illuminate and manipulate the behavior of intrinsically disordered proteins and their phase transitions.     

Chemical test methods for determining components of liquids

The reported data on determining substances by chemical test methods are summarized. The reagents used; methods of their immobilization on supports; and principles, devices, and methods for determining components are considered. The main analytical characteristics are discussed.     

Chemical interaction of flue gas components with the growth ofcyanidium caldarium

Applied Biochemistry and Biotechnology - Normal photosynthesis byCyanidium results in O2 evolution, suggesting that the uptake and subsequent reduction of CO2 also occur. This process, therefore,...     

Quantitative analysis of target components by comprehensive two-dimensional gas chromatography

Quantitative analysis using comprehensive two-dimensional (2D) gas chromatography (GC) is still rarely reported. This is largely due to a lack of suitable software. The objective of the present study is to generate quantitative results from a large GC x GC data set, consisting of 32 chromatograms. In this data set, six target components need to be quantified. We compare the results of conventional integration with those obtained using so-called "multiway analysis methods". With regard to accuracy and precision, integration performs slightly better than Parallel Factor (PARAFAC) analysis. In terms of speed and possibilities for automation, multiway methods in general are far superior to traditional integration.     

Chemical strategies and characterization tools for the organization of single molecule magnets on surfaces

Addressing individual bistable magnetic molecules, known as Single Molecule Magnets (SMMs), is a fascinating goal at the borderline between molecular magnetism and spin electronics. This tutorial review focuses on the first step towards single-molecule experiments, namely the organization of SMMs on surfaces. Both preparation and characterization of surface-supported SMMs prove to be quite demanding and a multidisciplinary approach is necessary, which is described here using selected examples. We first illustrate the chemical strategies devised to assemble SMMs and to control their orientation on surfaces. Then, we present characterization tools, which have been selected on the basis of their relevance to address specific points, i.e. the chemical composition of the deposited SMM films, the organization of the molecules on the surface, the intramolecular arrangement of the spins, the magnetic anisotropy of SMMs, and eventually the dynamics of their magnetization on surfaces. Particular attention is devoted to techniques exploiting synchrotron light.     

Chemical recycling of polyurethanes and separation of the components by supercritical ammonia

Chemical recycling of a polyurethane elastomer and a flexible foam based on methylenebis(phenyl isocyanate) (MDI) and a polyetherpolyol was performed by ammonolytic cleavage of urethane and urea bonds under supercritical conditions. Resulting products were the polyols, the amines corresponding to the isocyanates used, and unsubstituted urea. Under suitable conditions the polyetherpolyol was completely separated from the other ammonolysis products which in turn can be further separated and used for the manufacture of polyurethanes or for the synthesis of diisocyanates.     

Interaction of components in the RbI-CsI-CuI quasi-ternary system

Differential thermal and X-ray powder diffraction analyses were used for studying phase equilibria in the polythermal sections RbCu₂I₃-CsCu₂I₃, CsCu₂I₃-Rb₂CuI₃, Rb₂CuI₃-Cs₃Cu₂I₅, and Cs₃Cu₂I₅-RbI of the RbI-CsI-CuI quasi-ternary system. For the first time, the nature of the physicochemical interaction in the RbI-CsI-CuI quasi-ternary system was investigated, an isothermal section at 473 K was constructed, and the boundaries of the formation of solid solutions based on ternary iodides were determined. No formation of new intermediate compounds in the quasi-ternary system was detected.     

Inverse gas chromatographic and chemometric tools for determination of interactions between the components of polymeric composition

Compositions of polymers (polyethylene and polyuretane) and fillers (initial silica and silicas modified with: N-2-aminoethyl-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxy-silane, 3-merkaptopropyltrimethoxysilane, octyltriethoxysilane) were examined by inverse gas chromatography at 383 K. Small amounts of the following test solutes were injected to achieve the infinite dilution conditions: pentane, hexane, heptane, octane, nonane, dichloromethane, chloroform, carbon tetrachloride and 1,2-dichloroethane.The retention times for these test solutes were determined and Flory-Huggins parameters were calculated. Flory-Huggins parameters characterize interactions between components: - between composition and the test solute and χ^′23 - between polymer and filler in the composition.Values of both physicochemical parameters characterizing the examined materials were arranged in a matrix form: in the rows the compositions were enumerated at different temperatures whereas the columns contained the test solutes. After standardization the input matrix was subjected to principal component analysis. Three principal components explain more than 93% of the total variance in the data. Almost all test solutes carry very similar information. Therefore, it is justified to eliminate most of them from the series of test solutes.     

Chemical fractionation in the solar system

The cosmochemical and geochemical history of planetary material is reflected in relative and absolute abundances of two groups of trace elements; siderophiles and volatiles. Many of these elements can be determined at the requires levels only by radiochemical neutron activation analysis. The abundance patterns of elements in chondritic meteorites result from condensation processes in the solar nebula. The composition of planetisimals which bombarded the Moon is characterized from trace elements in lunar breccias, and is also related to nebula processes. Trace elements in anorthosites and basalts from Earth and Moon suggest that the Moon is refractory-rich and volatile-poor relative to the Earth.     

目标化合物析分系统中的重要算法

介绍了目标化合物析分系统中所用到的三个重要算法。它们是：最短拓扑距离的求解、析分过程结束的判别以及合成树的构建。分子结构中任意两个原子之间最短拓扑距离的求解是建立在采用队列数据结构的宽度优先搜索算法基础上的,析分过程结束的判别是由在新Morgan算法基础上产生的化合物的唯一编码和B－树两种算法构成,前者是为了将前体与原料库中每个化合物是否同构的复杂问题简化为码之间的比较问题;后者是一种高效文件组织方式,将代表原料库中化合物的唯一编码作为检索键来组织建库,从而实现对原料库的快速查询,合成树采用的是链表存储方式,每一个结点由六个域组成,且在建树和画树的过程中,均用前序遍历。这些算法是实现析分系统的基础,因此它们的正确设计与高效实现就显得尤为重要。