MASPIT: three-hybrid trap for quantitative proteome fingerprinting of small molecule-protein interactions in mammalian cells

Organic small molecules generally act by perturbing the function of one or more cellular target proteins, the identification of which is essential to an understanding of the molecular basis of drug action. Here we describe the application of methotrexate-linked small molecule ligands to a mammalian three-hybrid interaction trap for proteome-wide identification of small molecule targets, quantification of the targeting potency of unmodified small molecules for such targets in intact cells, and screening for inhibitors of small molecule-protein interactions. During the course of this study we also identified the pyrido[2,3-d]pyrimidine PD173955, a known SRC kinase inhibitor, as a potent inhibitor of several ephrin receptor tyrosine kinases. This finding could perhaps be exploited in the design of inhibitors for this kinase subfamily, members of which have been implicated in the pathogenesis of various diseases, including cancer.     

Minimally adhesive polymer surfaces prepared from star oligosiloxanes and star oligofluorosiloxanes

The effects of the surface energy, storage modulus (G′), and glass‐transition temperature (T_g) on the biofouling behavior of siloxane and fluorosiloxane polymer surfaces (films) were studied. Irregular Si? H‐terminated tetrabranched star oligosiloxanes and star oligofluorosiloxanes were prepared by the acid‐catalyzed equilibration of octamethylcyclotetrasiloxane or 1,3,5‐trimethyl‐1,3,5‐tris(3′,3′,3′‐trifluoropropyl)cyclotrisiloxane with tetrakis(dimethylsiloxy)silane, respectively. Terminal epoxy groups were introduced via Pt‐catalyzed hydrosilylation with allyl glycidyl ether to yield compounds that were subsequently crosslinked with α,ω‐bis(3‐aminopropyl)poly(dimethylsiloxane). The resulting films were characterized by goniometry, dynamic mechanical thermal analysis, and thermogravimetric analysis. The foul‐release behavior was studied by the measurement of how strongly sporelings (young plants) of the green seaweed Ulva adhered. The corrosion protection of aluminum was evaluated by electrochemical impedance spectroscopy. Fluorosiloxane films displayed higher G′ and T_g values, decreased contact angles (with water), and more effectively released Ulva sporelings in comparison with siloxane films. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2551–2566, 2006     

Band fluorescence of xenon

The Xe₂ emission band at 168 nm has been observed during irradiation of xenon gas with the 147 nm resonance line. The band is attributed to Xe₂ molecules formed by reaction between ground-state and metastable (2_u) xenon atoms.     

Room‐Temperature Formation Pathway for CdTeSe Alloy Magic‐Size Clusters

Little is known about the pathway of room‐temperature formation of ternary CdTeSe magic‐size clusters (MSCs) obtained by mixing binary CdTe and CdSe induction period samples containing binary precursor compounds (PCs) of MSCs, monomers (Ms), and fragments (Fs). Also, unestablished are dispersion effects that occur when as‐mixed samples (without incubation) are placed in toluene (Tol) and octylamine (OTA) mixtures. The resulting ternary MSCs, exhibiting a sharp optical absorption peak at 399 nm, are labelled CdTeSe MSC‐399, and their PCs are referred to as CdTeSe PC‐399. When the amount of OTA is relatively small, single‐ensemble MSC‐399 evolved without either binary CdTe or CdSe MSCs. When the OTA amount is relatively large, CdTe MSC‐371 appeared initially and then disappeared, while single‐ensemble MSC‐399 developed more deliberately. The larger the OTA amount, the more slowly these changes proceeded. The substitution reaction of CdTe PC + CdSe M/F?CdTeSe PC‐399 + CdTe M/F is proposed to be rate‐determining for the MSC‐399 formation in a Tol and OTA mixture. This study provides further understanding of the transformation pathway between MSCs.     

End-stapled homo and hetero collagen triple helices: a click chemistry approach

A CuAAC reaction was established for modular synthesis of end-stapled homo- and hetero-triple helical peptides, generating "clicked" macro-assemblies with enhanced thermal stability.     

Cranberry proanthocyanidins mediate growth arrest of lung cancer cells through modulation of gene expression and rapid induction of apoptosis

Cranberries are rich in bioactive constituents purported to enhance immune function, improve urinary tract health, reduce cardiovascular disease and more recently, inhibit cancer in preclinical models. However, identification of the cranberry constituents with the strongest cancer inhibitory potential and the mechanism associated with cancer inhibition by cranberries remains to be elucidated. This study investigated the ability of a proanthocyanidin rich cranberry fraction (PAC) to alter gene expression, induce apoptosis and impact the cell cycle machinery of human NCI-H460 lung cancer cells. Lung cancer is the leading cause of cancer-related deaths in the United States and five year survival rates remain poor at 16%. Thus, assessing potential inhibitors of lung cancer-linked signaling pathways is an active area of investigation.     

A liquid chromatography/tandem mass spectrometry (LC-MS/MS) method for the determination of phenolic polycyclic aromatic hydrocarbons (OH-PAH) in urine of non-smokers and smokers

Polycyclic aromatic hydrocarbons (PAH) are products of the incomplete combustion of organic materials and, therefore, occur ubiquitously in the environment and also in tobacco smoke. Since some PAH have been classified as carcinogens, it is important to have access to suitable analytical methods for biomarkers of exposure to this class of compounds. Past experience has shown that measuring a profile of PAH metabolites is more informative than metabolites of a single PAH. Assessment of environmental and smoking-related exposure levels requires analytical methods with high sensitivity and specificity. In addition, these methods should be fast enough to allow high throughput. With these pre-conditions in mind, we developed and validated a high-performance liquid chromatographic method with tandem mass spectrometric detection (LC-MS/MS) for the determination of phenolic metabolites of naphthalene, fluorene, phenanthrene and pyrene in urine of smokers and non-smokers. Sample work-up comprised enzymatic hydrolysis of urinary conjugates and solid-phase extraction on C18 cartridges. The method showed good specificity, sensitivity, and accuracy for the intended purpose and was also sufficiently rapid with a sample throughput of about 350 per week. Application to urine samples of 100 smokers and 50 non-smokers showed significant differences between both groups for all measured PAH metabolites, and strong correlations with markers of daily smoke exposure in smoker urine. Urinary levels were in good agreement with previously reported data using different methodologies. In conclusion, the developed LC-MS/MS method is suitable for the quantification of phenolic PAH metabolites of naphthalene, fluorene, phenanthrene, and pyrene in smoker and non-smoker urine.     

Engineering of biocatalysts - from evolution to creation

Enzymes are increasingly being used in an industrial setting as a cheap and environmentally-friendly alternative to chemical catalysts. In order to produce the ideal biocatalyst, natural enzymes often require optimization to increase their catalytic efficiencies and specificities under a particular range of reaction conditions. A number of enzyme engineering strategies are currently employed to modify biocatalysts, improving their suitability for large-scale industrial applications. These include various directed evolution techniques, semi-rational design techniques, and more recently, the de novo design of novel enzymes. Advances in mutant library design, high-throughput selection processes, and the introduction of powerful computer algorithms have all contributed to the current exponential growth of the field of enzyme engineering. This review article aims to present some of the currently employed strategies for enzyme engineering and attempts to highlight the most recent advances in methodology.     

Effect of molecular weight on conductivity of polymer electrolytes

The ionic conductivity, σ, of mixtures of poly(ethylene oxide) (PEO) and lithium bis(trifluoromethanesulfone)imide (LiTFSI) was measured as a function of molecular weight of the PEO chains, M, over the range 0.2-5000 kg/mol. Our data are consistent with an expression σ = σ₀ + K/M proposed by Shi and Vincent [Solid State Ionics 60 (1993)] where σ₀ and K are exponential and linear functions of inverse temperature respectively. Explicit expressions for σ₀ and K are provided.     

Performance and pathways of electrochemical cyclohexane oxidation

Falling costs of electricity from renewable and non-renewable sources have motivated interest in electrochemical production of chemicals and fuels. Among commodity chemicals, the production of KA oil (cyclohexanol and cyclohexanone) from cyclohexane is attractive as selective alkane oxidation remains a major industrial challenge. Although this reaction has been demonstrated in the literature, its fundamental chemistry remains poorly understood. This review identifies possible pathways for the reaction mechanism, their experimental support, and remaining critical gaps in molecular understanding of electrochemical cyclohexane oxidation to KA oil.