Effective recovery by KCl precipitation of highly diluted muscle proteins solubilized with sodium dodecyl sulfate.

A new, improved method is described, which takes advantage of the low solubility of potassium dodecyl sulfate (KDS), to concentrate sodium dodecyl sulfate-solubilized proteins from nanomolar solutions by KDS precipitation. The method was applied to proteins differing in Mr and pI. The effect of varying KCl, and the pH and/or concentration of the buffer on KDS-protein precipitation was studied. These parameters may be chosen to allow selective repartition of specific proteins in the pellet or supernatant. After precipitation, the hundred- or thousand-fold concentrated solutes are easily resuspended in small volumes of any required medium. Though initially experimented to recover muscle proteins from effluents of electroendosmotic preparative gel electrophoresis, the method proved to be of general interest as a powerful tool to recover proteins from highly diluted solutions.     

Results from the kaonic hydrogen X-ray measurement at DAFNE and outlook to future experiments

The $\overline{K}N$ system at rest plays a key role for the understanding of strong interaction of hadrons with strangeness involved. The experiment SIDDHARTA used X-ray spectroscopy of kaonic atoms to measure the strong interaction induced shift and width of the ground state. It was the first experiment on kaonic He3 and deuterium ever, kaonic hydrogen was measured with improved precision resulting in $\epsilon_{1s} = -283 \pm 36 \mbox{(stat)} \pm 6 \mbox{(syst)}$ eV and $\Gamma_{1s} = 541 \pm 89 \mbox{(stat)} \pm 22 \mbox{(syst)}$ eV. Additionally a scheme for an improved future experiment on kaonic deuterium is introduced in this contribution.     

Simultaneous photoproduction of eta and pi0 mesons on the proton

The analysis of the gammap-->etapi(0)p reaction has been performed using data from the GRAAL experiment. The total and differential cross sections and the beam asymmetry have been obtained from threshold up to 1.5 GeV of beam energy. The two resonances S11(1535) and Delta(1700) are expected to be excited in the intermediate states of this reaction. The results are used to test predictions based on the assumption that both resonances are dynamically generated from the meson-baryon interaction provided by chiral Lagrangians. The term involving the Delta(1700) excitation, followed by the decay into etaDelta(1232), is found to be dominant.     

Fully reversible procedure for silver staining improves densitometry of complex mixtures of biopolymers resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis

Due to its high sensitivity, silver staining is a widely popular method for the revelation of biopolymers separated by both native and denaturing electrophoresis. A step-by-step method for the destaining and restaining of overdeveloped/overloaded silver-stained bands is described that is applicable to both proteins and nucleic acids. The procedure significantly improves densitometric analysis of gels that have been silver stained with either commercial kits or solutions made in-house. The method permits reproducible densitometry of silver-stained gels and allows quantification of both main and minor components in complex mixture of molecules resolved on the same gel slab. All steps may be interrupted and are readily reversible, allowing for facile densitometric analyses and photographic recording under optimized conditions. Furthermore, common artifacts such as differential staining of the two gel surfaces, localized uneven yellow-ochre background, and the presence of fold marks and fingerprints can be easily removed.     

Über die Verwendung der Groldbromwasserstoffsäure zum mikrochemischen Nachweis von Alkaloiden und organischen Basen

Zusammenfassung Es wird vorgeschlagen, die Goldbromwasserstoffsäure für den mikro-chemischen Nachweis von Alkaloiden und organischen Basen zu verwenden und es werden die mit Pyridinbasen und Chinolinbasen erhaltenen Produkte beschrieben. Besonderes Interesse verdienen die mit Coffein. Theobromin und Theophyllin erhaltenen Kristallfällungen, da sie eine Unterscheidung der genannten Basen gestatten.

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Summary The use of bromauric acid is proposed for the microchemical identification of alkaloids and organic bases and the products obtained from pyridine and quinoline bases are described. Special interest attaches to the crystalline precipitates given by coffeine, theobromine and theophylline since they permit a differentiation of these bases.

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Résumé II est recommandé d'employer l'acide auribrombydrique pour l'identification microchimique des alcaloïdes et des bases organiques; l'auteur décrit en outre le comportement des produits obtenus en présence des bases pyridiniques et quinoléiniques. Les précipitations cristallines que l'on obtient avec la caféine, la théobromine et la théophylline méritent un intérêt particulier car elles constituent une différenciation de ces bases.

     

Monoximes and dioximes of 2,1,3-benzothiadiazole dignes

NMR spectra, in organic solvents, and dissociation constants in water, have been determined for a series of monoximes, dioximes and mono-O-methyldioximes of 2,1,3-benzothiazole-4,5 and 4,7-dione. On the basis of NMR data “4 - hydroxy - 5 - nitroso-, 4 - hydroxy - 7 - nitroso- and 5 - hydroxy - 4 - nitroso -2,1,3- benzothiadiazole” exist predominantly in quinonemonoxime forms. Configurations were assigned to geometrical isomers. The 4,5- and 4,7 - di - O - methyidioximinobenzothiadiazoles were also investigated. Four and two geometrical isomers of the 4,5- and 4,7-derivatives, respectively, have been separated, and the physical and spectral properties of each isomer are described.     

Synthesis of oxazolidin-2-ones using carbonate ion on a polymeric support

Through the insertion of a carbon dioxide molecule, the oxazolidin-2-ones ($\text{5a}$) and ($\text{5b}$) were prepared by treataent of the salts ($\text{4a}$) and ($\text{4b}$) with carbonate anion on polymeric support. The hydrolysis under basic conditions of ($\text{5a}$) and ($\text{5b}$) afforded the erythro-3-amino-1,2-diols ($\text{6a}$) and ($\text{6b}$) which were fully acetylated: the 2-amino-2-deoxyerythritol derivative ($\text{7b}$) was obtained in 91% yield.     

The one-dimensional Lennard-Jones system: collective fluctuations and breakdown of hydrodynamics

The dynamical correlations of a model consisting of particles constrained on the line and interacting with a nearest-neighbour Lennard-Jones potential are computed by molecular-dynamics simulations. A drastic qualitative change of the spectral shape, from a phonon-like to a diffusive form, is observed upon reducing the particle density even ad moderate temperatures. The latter scenario is due to the spontaneous fragmentation of the crystal-like structure into an ensemble of “clusters" colliding among themselves. In both cases, the spectral linewidths do not follow the usual q² behaviour for small wavenumbers q, thus signalling a breakdown of linearized hydrodynamics. This anomaly is traced back by the presence of correlations due to the reduced dimensionality.