Plasma desorption mass spectrometry of biomolecules

In the present work the positive and negative ion mass spectrum of nine xenobiotica metabolites conjugated with N-acetyl-cysteine (=mercapturic acids) were investigated. Whereas in the positive ion spectra most fragment ions are correlated to the backbone of the mercapturic acids the negative ion spectra were dominated by the ionized side chain. Further the peptidoglycans of the cell walls of the cyanelles of Cyanophora paradoxa and of Escherichia coli were characterized by high performance liquid chromatography / plasma desorption mass spectroscopy off line. Some contributions were also done for the elucidation of suppression effects in the mass spectrometric mixture analysis of peptides. These suppression effects were correlated to peptide hydrophobicity / hydrophilicity, peptide net charge and peptide gas phase basicity. A very interesting contribution to this work was the development of a new, chloroform-resistant matrix for plasma desorption mass spectrometry with the use of the low molecular weight compound 3-(3-pyridyl) acrylic acid. With this matrix material a wide variety of different classes of compounds was investigated including peptides, glycopeptides and phospholipides. (author)