Electron ionization mass spectrometric study of monomeric models of O-polysaccharides of Vibrio cholerae O:1, serotypes Ogawa and Inaba.

Fragmentation mechanisms of electron ionization (EI) mass spectrometry of the title compounds have been elucidated by high-resolution (HR) mass spectrometric measurements of the elemental composition and measurements of the metastable transitions (B(2)/E, CID). The experimental results were interpreted with the help of Mass Frontier 3.0 software, which aided the elucidation of fragmentation mechanisms and helped to deduce structures of the ions formed.

Electron ionization (EI) mass spectra of exo-endo double-bond isomers of polycyano "push-pull" pentadienes derived from cycloalkylidene malonic acid derivatives.

The title compounds, which exist in solutions as mixtures of exo/endo double bond isomers due to the "push-pull" effect of the electron-donating and electron-withdrawing substituents, were studied by mass-spectrometric methods. Their fragmentation routes under electron impact were established and confirmed by metastable ion analysis and accurate mass measurements. The results demonstrated that the relative amounts of exo/endo isomeric molecular ions are in close agreement with the isomeric ratios observed in solutions by the NMR, although the mass spectra of the tetracyano derivatives indicated a small fraction of molecular ions existing in the endo form, which could not be detected in solution by the NMR methods.

Phytosterols in sea buckthorn (Hippophaë rhamnoides L.) berries: identification and effects of different origins and harvesting times.

Sterols in seeds, pulp/peel fractions, and whole berries of sea buckthorn (Hippophaë rhamnoides L.) samples belonging to two major subspecies (sinensis and rhamnoides) from Finland and China were analyzed as TMS derivatives by gas chromatography-mass spectrometry after saponification of the oils. The total sterol contents in the seeds, the fresh pulp/peel, and the whole berries were 1200-1800, 240-400, and 340-520 mg/kg, respectively.

1H-NMR studies on association of mRNA cap-analogues with tryptophan-containing peptides.

1H-NMR spectroscopy was applied to a study of the mode of interaction, in aqueous medium in the pH range 5.2-8.5 and at low and high temperatures, between several mono- and dinucleotide analogues of the mRNA cap m7GpppG and a selected tripeptide Trp-Leu-Glu, and a tetrapeptide Trp-Glu-Asp-Glu, the sequence of which corresponds to one of the suspected binding sites in the mRNA cap-binding protein (CBP).

Muramic acid in peripheral blood leukocytes of healthy human subjects.

Peptidoglycan, a specific marker for all bacterial cell walls, was studied in peripheral blood of healthy human subjects by mass spectrometric analysis of muramic acid. Peripheral blood mononuclear and polymorphonuclear cells from 98 healthy adults were hydrolyzed and analyzed by gas chromatography-mass spectrometry as alditol acetate derivatives using selective ion monitoring. Muramic acid was observed in cell samples from 21 of 98 subjects.