Lasing of iodine in the fullerene-oxygen-iodine system

The possibility of lasing in the fullerene-oxygen-iodine system with optical excitation of fullerene is studied. Laser radiation with an energy of 25 mJ and a pulse duration of 5–10 ms is obtained.     

Application of stir bar sorptive extraction for wine analysis

Stir bar sorptive extraction (SBSE) coupled with gas chromatography/mass spectrometry (GC/MS) was used to analyse wine samples for three applications: flavour and compositional analysis; 2,4,6-trichloroanisole (TCA), a common off-aroma in wine; and agrochemicals. SBSE was found to be orders of magnitude more sensitive than modern conventional methodology, allowing for lower detection and quantitation levels, and improved confirmation of identity; SBSE often gave better signal to noise in scan mode than other methods in selective ion monitoring (SIM) mode. With the help of their characteristic mass spectra all agrochemicals could be identified unambiguously at concentrations of 10 microg L(-1) in wine and a further 100 constituents were detected in a Cabernet Sauvignon sample. Thus it is now possible to analyse complex samples such as wine by scan mode, with better confirmation of identity, and without sacrificing sensitivity, where previously SIM methodology had to be used.     

Synthesis and characterization of polymers produced by horseradish peroxidase in dioxane

Polymers were synthesized from substituted phenolic and aromatic amine compounds with hydrogen peroxide as the source of an oxidizing agent and horseradish peroxidase enzyme as the catalyst. The polymerization reaction was carried out in a monophasic organic solvent with small amounts of water at room temperature. Conditions for the synthesis of polymers with respect to reaction time and yield were studied with a number of monomers at different concentrations and in solvents with different buffers with pH range of 5.0–7.5. Physical and chemical properties of these homo-and copolymers were determined with respect to melting point, solubility, elemental analysis, molecular weight distribution, infrared absorption (including FTIR), solid-state ¹³C nuclear magnetic resonance, thermal gravimetric analysis, and differential scanning calorimetry. The enzyme catalyzed reactions produced polymers of molecular weight greater than 400,000 which were further fractionated by differential solubility in solvent mixtures and the molecular weight distribution of the polymer fractions were determined. In general, the polymers synthesized have low solubilities, high melting points, and some degree of branching.     

Evaluation of automated nano-electrospray mass spectrometry in the determination of non-covalent protein-ligand complexes

The use of electrospray ionization mass spectrometry (ESI-MS) for studying non-covalent interactions between macromolecules and ligands is well established. ESI-MS can be a useful tool for the determination of dissociation constants between molecules in the gas phase. We validate this method by studying the binding of the catalytic domain of cellobiohydrolase I (CBH I) from Trichoderma reesei to the disaccharide inhibitor cellobiose. The method was further applied to study two newly synthesized cellobiose derivatives (m-iodobenzyl 2-deoxy-2-azido-beta-cellobioside and p-benzyloxybenzyl beta-cellobioside). In a titration experiment, peak areas of different charge states of the free enzyme and the complex were summed in order to determine the dissociation constant. For cellobiose and m-iodobenzyl 2-deoxy-2-azido-beta-cellobioside, the calculated values are in good agreement with those reported from either displacement titration or equilibrium binding experiments in solution. Due to non-specific binding, the dissociation constant of p-benzyloxybenzyl beta-cellobioside does not correspond with the solution-based value. Our results indicate the need for careful interpretation of data sets when using nanoESI to study non-covalent interactions.     

Comparison of a pump-around, a diffusion-driven, and a shear-driven system for the hybridization of mouse lung and testis total RNA on microarrays

In the present study, we demonstrate the benefits of a shear-driven rotating microchamber system for the enhancement of microarray hybridizations, by comparing the system with two commonly used hybridization techniques: purely diffusion-driven hybridization under coverslip and hybridization using a fully automated hybridization station, in which the sample is pumped in an oscillating manner. Starting from the same amount of DNA for the three different methods, a series of hybridization experiments using mouse lung and testis DNA is presented to demonstrate these benefits. The gain observed using the rotating microchamber is large: both in terms of analysis speed (up to tenfold increase) and in final spot intensity (up to sixfold increase). The gain is due to the combined effect of the hybridization chamber miniaturization (leading to a sample concentration increase if comparing iso-mass conditions) and the transport enhancement originating from the rotational shear-driven flow induced by the rotation of the chamber bottom wall.     

High-throughput chemistry toward complex carbohydrates and carbohydrate-like compounds

In the area of peptide and nucleic acid chemistry and biology, high-throughput synthesis has played an important role in providing useful small-molecule-based chemical probes in understanding the structure and function relationships. The past several years, there has been a constant rise in interest toward understanding the biological roles and functions of another important class of biomolecules, i.e., carbohydrates and carbohydrate conjugates. Although at early stages, in recent years, several groups have developed high-throughput synthetic methods to obtain complex carbohydrates or carbohydrate-like small-molecules. The present review article summarizes some of these developments.     

Can magnetic circular dichroism tackle the problem of site symmetry in solutions?

A new approach to unravel the site symmetry of lanthanides in solutions is presented. The magnetic circular dichroism spectra of Eu³⁺ in the symmetries D_3h, C_4v and D_2d are simulated. In these simulations, the main idea is to introduce the magnetic field along a 3-fold axis, being the resultant of the three equivalent X-, Y- and Z-direction of a cube. This implies that the parallel and perpendicular Zeeman effects are taken into account simultaneously.     

Design, synthesis, and evaluation of a radicicol and geldanamycin chimera, radamide

A chimera composed of the natural products radicicol and geldanamycin has been prepared through an amide linkage connecting the resorcinol moiety of radicicol to the quinone ring of geldanamycin. The inhibitory activity of these compounds was determined by their ability to inhibit Hsp90's inherent ATPase activity along with degradation of the Hsp90 client protein, HER-2 in MCF-7 breast cancer cells. [reaction: see text]     

Brain gangliosides: an improved simple method for their extraction and identification

Total ganglioside extracts prepared from brain tissue were concentrated either by dialysis against Carbowax or by employing Millipore filter cones. Thin-layer chromatography was then carried out using silica gel plates. After location of the various fractions quantitation was effected by direct densitometry. The methods that have been adopted are rapid and suitable for the study of brain gangliosides in post mortem and biopsy material in a clinical chemistry laboratory.