Fragmentation of Biomolecular Ions

The studies of biomolecules (DNA components such as bases, phosphate, deoxyribose, or hydration water) in isolated conditions are of fundamental interest for modeling their behavior in real biosystems, e.g., during exposure to ionizing radiation. The yield of several anions, formed by dissociative electron attachment to gas phase biomolecules, exhibits the same electron energy dependence as the yield of single and double strand breaks of plasmid DNA attached to a surface. This indicates that the formation of transient negative ions plays an important role in radiation damage of cells and living organisms. Scientists all over the world have probed the inelastic interaction of electrons with gas phase biomolecules, utilizing electron transmission spectroscopy and mass spectrometry. In all of these studies the target molecules were vaporized in an oven at temperatures up to 500K. So far, all mass spectrometric investigations were probing ions that are formed in the ion source and do not decay on their way to the detector. By means of sector field mass spectrometry it is planned to study unimolecular and collision induced dissociation reactions of positively and negatively charged product ions generated upon electron collisions with gas phase biomolecules. The correlation between fragmentation patterns and the arrangement of the atoms of the precursor ion can be used to probe temperature induced modifications of neutral biomolecules such as isomerization, tautomerization or thermal decomposition. In addition, the careful analysis of the shape of the parent and fragment ion yield gives access to the kinetic energy release distribution of a decay reaction. The kinetic energy that is released in a fragmentation process determines how far from the point of formation reactive fragments can migrate and induce further damage to the biological system. Seeded beams and pickup of gas phase biomolecules with cold rare gas clusters (including helium clusters) will be used to cool the gas phase biomolecules prior to the interaction with the electron beam. Furthermore, it is planned to develop a source to bring large and complex biomolecules such as short sequences of DNA into the gas phase. Spray sources seem to be the appropriate technique, however, in contrast to electrospray the source will be optimized for NEUTRAL molecules. The group of Prof. Hvelplund in Aarhus will support us with know-how in the construction and operation of spray sources.

The studies of biomolecules (DNA components such as bases, phosphate, deoxyribose, or hydration water) in isolated conditions are of fundamental interest for modeling their behavior in real biosystems, e.g., during exposure to ionizing radiation. The yield of several anions, formed by dissociative electron attachment to gas phase biomolecules, exhibits the same electron energy dependence as the yield of single and double strand breaks of plasmid DNA attached to a surface. This indicates that the formation of transient negative ions plays an important role in radiation damage of cells and living organisms. Scientists all over the world have probed the inelastic interaction of electrons with gas phase biomolecules, utilizing electron transmission spectroscopy and mass spectrometry. In all of these studies the target molecules were vaporized in an oven at temperatures up to 500K. So far, all mass spectrometric investigations were probing ions that are formed in the ion source and do not decay on their way to the detector. By means of sector field mass spectrometry it is planned to study unimolecular and collision induced dissociation reactions of positively and negatively charged product ions generated upon electron collisions with gas phase biomolecules. The correlation between fragmentation patterns and the arrangement of the atoms of the precursor ion can be used to probe temperature induced modifications of neutral biomolecules such as isomerization, tautomerization or thermal decomposition. In addition, the careful analysis of the shape of the parent and fragment ion yield gives access to the kinetic energy release distribution of a decay reaction. The kinetic energy that is released in a fragmentation process determines how far from the point of formation reactive fragments can migrate and induce further damage to the biological system. Seeded beams and pickup of gas phase biomolecules with cold rare gas clusters (including helium clusters) will be used to cool the gas phase biomolecules prior to the interaction with the electron beam. Furthermore, it is planned to develop a source to bring large and complex biomolecules such as short sequences of DNA into the gas phase. Spray sources seem to be the appropriate technique, however, in contrast to electrospray the source will be optimized for NEUTRAL molecules. The group of Prof. Hvelplund in Aarhus will support us with know-how in the construction and operation of spray sources.