Performance of a nuclear microprobe to study giant marine aerosol particles

The scanning nuclear microprobe analytical facility of the IRMM was used to determine with PIXE major, minor and trace elements in individual giant marine aerosol particles, collected above the North Sea (particle size > 5 m Ø). The instrumentation is briefly described, and the experimental parameters chosen for these analyses are discussed. Elements with atomic numbers Z > 15 could be determined. Detection limits observed under the prevailing experimental conditions reached down to 50 fg in the case of Ti, V or Cr, corresponding to a mass content of 10 g/g in particles of 15 m size. Quantitative evaluation of the acquired spectra revealed basically three aerosol types in these samples: sea salt particles, sea salt combined with high contents of S, K and Ca, and particles rich in heavier elements (Ti, Cr, Fe, Ni). The agglomeration of several large particles forming a giant one could be visualised directly through the heterogeneity found in the elemental maps of such a particle.     

Capillary electrophoresis-mass spectrometry for glycoscreening in biomedical research

Application of capillary electrophoresis (CE) in combination with mass spectrometry (MS) and tandem MS to glycoscreening in biomedical projects is highlighted. In the first part recent CE-MS experiments by sheath liquid CE and multiple stage MS are reported. Neutral and negatively charged N-glycan mixtures from ribonuclease B and fetuin, high-mannose type N-glycoforms, oligosaccharides from lipopolysaccharides (LPS) of Haemophilus influenzae, polysaccharides of Pseudomonas aeruginosa and Staphylococcus aureus were analyzed. A particular emphasis is devoted to the applicability of novel off- and on-line CE-MS and tandem MS methods for screening of proteoglycan-derived oligosaccharides, glycosaminoglycans (GAGs), such as hyaluronates from Streptococcus agalactiae, chondroitin/dermatan sulfates (CS/DS) from bovine aorta and human skin fibroblast decorin, and heparin/heparan sulfate (HS) from porcine and bovine mucosa. The performance of CE-MS/MS for identification of glycoforms in glycopeptides and glycoproteins is illustrated by experiments performed on complex mixtures from urine of patients suffering from a hereditary N-acetylhexosaminidase deficiency (Schindler's disease) and urine of patients suffering from cancer cachexia. For determination of glycosylation patterns in glycoproteins like enzymes and antibodies by CE/MS, both CE-matrix assisted laser desorption/ionization (MALDI) and CE-electrospray ionization (ESI)-MS were functional. Finally, the potential of CE-ESI-MS strategy in glycolipid analysis is demonstrated for gangliosides from bovine brain for which particular CE buffer conditions are required.     

Synthesis and Structures of the Novel Pyridoxal Oxime Derivatives

Novel pyridoxal oxime derivatives were prepared and characterized by means of IR, ¹H and ¹³C NMR spectroscopy. The crystal structures of the 3-hydroxy-4-hydroxyiminomethyl-5-hydroxymethyl-1,2-dimethylpyridinium iodide 1 and 3-hydroxy-4-hydroxyiminomethyl-5-hydroxymethyl-1,2-dimethylpyridinium chloride monohydrate 2 were determined by X-ray analysis. The both compounds crystallize in the triclinic crystal system, space group P . Crystal data: 1 a = 6.286(2) Å, b = 8.748(4) Å, c = 11.736(4) Å, = 104.02(3)°, = 94.70(3)°, = 107.44(6)°, V = 589.0(4) ų, Z = 2, R = 0.0526; 2 a = 6.8980(5) Å, b = 8.6409(6) Å, c = 11.1777(6) Å, = 111.138(5)°, = 93.114(6)°, = 105.158(5)°, V = 591.57(7) ų, Z = 2, R = 0.0492. The bond distances and angles in both structures agree very well. The main difference between these structures was observed in the orientation of the hydroxymethyl group with respect to the pyridinium ring. In the both structures intramolecular hydrogen bond forming six-membered ring were observed. The intermolecular OsI hydrogen bonds in the crystal structure of the compound 1 form dimers. In the crystal structure of compound 2, the water molecules and chlorines build eight-membered rings, which are also connected to pyridinium cations by OsCl and OsO intermolecular hydrogen bonds forming a three-dimensional network.     

Sialylation analysis of O-glycosylated sialylated peptides from urine of patients suffering from Schindler's disease by Fourier transform ion cyclotron resonance mass spectrometry and sustained off-resonance irradiation collision-induced dissociation

A strategy based on Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) for screening of complex glycoconjugate mixtures containing O-linked glycopeptides and O-glycosylated amino acids with alpha-N-acetylgalactosaminyl residues is presented. To detect and identify O-glycoforms present in urine of patients suffering from hereditary N-acetylhexosaminidase deficiency (known as Schindler's disease), present at 100 times higher concentrations than in urine of healthy controls, new accurate methods for mapping and sequencing were required. In the mass spectrometric analysis particular attention has to be paid to original sialylation patterns, because of the potential lability of the sialic acid moiety during the desorption/ionization process. Negative ion nanoelectrospray ionization (nanoESI) FTICR-MS at 9.4 T is shown here to represent a method of choice for identification of single components in such complex glycomixtures due to high resolution and mass accuracy. By optimization of sustained off-resonance irradiation collision-induced dissociation tandem mass spectrometry (SORI-CID-MS(2)) in the negative ion mode, the type and sequence of the sialylated glycopeptide components were determined from their fragmentation patterns. Additionally, implementation of SORI-CID-MS(3) provides detailed information for sialylation analysis. The potential diagnostic value of this approach is discussed.     

Variational construction of diabatic states

The previously proposed local variational algorithm for generating diabatic states from adiabatic states is tested numerically for the simplest case of avoided potential curve crossing in a diatomic. The obtained results fully agree with those found by an interpolation scheme.     

Screening and sequencing of complex sialylated and sulfated glycosphingolipid mixtures by negative ion electrospray Fourier transform ion cyclotron resonance mass spectrometry

A protocol for negative ion nanoelectrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (-)nanoESI-FTICR MS, investigation of complex biological mixtures consisting of sialylated or sulfated glycosphingolipids (GSL) expressing high heterogeneity in the ceramide portion is described. Different instrumental and solvent conditions were explored and optimized to promote efficient ionization, reduce the in-source fragmentation and consequently enhance the detection of intact molecular species from complex mixtures. Using the novel optimized (-)nanoESI-FTICR MS protocol, a reliable and detailed compositional fingerprint of the polysialylated ganglioside mixture isolated from human brain was obtained. Sustained off-resonance irradiation collision-induced dissociation mass spectrometry (SORI-CID MS2) was introduced for the first time for structural elucidation of polysialylated gangliosides. Under well-defined conditions, an informative fragmentation pattern of the trisialylated ganglioside GT1 was obtained. The compositional mapping of a complex mixture of sulfated glucuronic acid containing neolacto-series GSLs extracted from bovine Cauda equina provided hard evidence upon previously described components and new structures not identified before by any other analytical method. Negative ion nanoESI-FTICR MS at 9.4 T is shown here to represent a valuable method in glycolipidomics, allowing a high resolution and mass accuracy detection of major and minor GSL glycoforms and identification of known and novel biologically relevant structures.     

<Superscript>0,2</Superscript>A<Subscript>n</Subscript> cross-ring cleavage as a general diagnostic tool for glycan assignment in glycoconjugate mixtures

In contrast to proteomics significantly less efficient analytical tools are presently available for high throughput glycomics using mass spectrometry. In this article, a strategy to use the (0,2)A(n) ring cleavage ion at the reducing end of free glycans as a diagnostic ion for assignment of free glycans, in presence of glycopeptides containing similar glycosylation patterns, is presented for rapid distinction in complex mixtures by mass spectrometry. The MS to MS/MS automatic switching, already previously introduced for the on-line LC-MS and CE-MS analysis, is shown in this contribution to be highly functional to obtain diagnostic fragmentation patterns of free glycan precursors in rapid screening of highly complex glycoconjugate mixtures obtained from clinical samples, namely from the urine of patients suffering from congenital disorders of glycosylation. Congenital disorders of glycosylation (CDG) are inherited metabolic diseases based on defects in the glycosylation pathways of glycoconjugates. The urine of CDG patients was reported to contain O-glycans and glycosylated amino acids at concentrations two to three orders of magnitude higher in comparison with the healthy control, characterized by a high degree of heterogeneity concerning the type, number, and values of molecular ions. Using the (0,2)A(n) ring cleavage ion approach by tandem MS, it was possible to sort out free glycans and get them assigned.     

Application of thin‐layer chromatography/infrared matrix‐assisted laser desorption/ionization orthogonal time‐of‐flight mass spectrometry to structural analysis of bacteria‐binding glycosphingolipids selected by affinity detection

Glycosphingolipids (GSLs) play key roles in the manifestation of infectious diseases as attachment sites for pathogens. The thin‐layer chromatography (TLC) overlay assay represents one of the most powerful approaches for the detection of GSL receptors of microorganisms. Here we report on the direct structural characterization of microbial GSL receptors by employment of the TLC overlay assay combined with infrared matrix‐assisted laser desorption/ionization orthogonal time‐of‐flight mass spectrometry (IR‐MALDI‐o‐TOF‐MS). The procedure includes TLC separation of GSL mixtures, overlay of the chromatogram with GSL‐specific bacteria, detection of bound microbes with primary antibodies against bacterial surface proteins and appropriate alkaline phosphatase labeled secondary antibodies, and in situ MS analysis of bacteria‐specific GSL receptors. The combined method works on microgram scale of GSL mixtures and is advantageous in that it omits laborious and time‐consuming GSL extraction from the silica gel layer. This technique was successfully applied to the compositional analysis of globo‐series neutral GSLs recognized by P‐fimbriated Escherichia coli bacteria, which were used as model microorganisms for infection of the human urinary tract. Thus, direct TLC/IR‐MALDI‐o‐TOF‐MS adds a novel facet to this fast and sensitive method offering a wide range of applications for the investigation of carbohydrate‐specific pathogens involved in human infectious diseases. Copyright © 2010 John Wiley & Sons, Ltd.