Selective Bond Cleavage in Potassium Collisions with Pyrimidine Bases of DNA

Abstract

We present negative ion formation from collisions of neutral potassium atoms with D-ribose (C 5 H 10 O 5 ), the sugar unit in the DNA/RNA molecule. From the negative ion time-of-flight (TOF) mass spectra, OH − is the main fragment detected in the collision range 50-100 eV accounting on average for 50% of the total anion yield. Prominence is also given to the rich fragmentation pattern observed with special attention to O − (16 m/z) formation. These results are in sharp contrast to dissociative electron attachment experiments. The TOF mass spectra assignments show that these channels are also observed, albeit with a much lower relative intensity. Branching ratios of the most abundant fragment anions as a function of the collision energy are obtained, allowing to establish a rationale on the collision dynamics. © 2013 AIP Publishing LLC. [http://dx

Communication: Site-selective bond excision of adenine upon electron transfer

“…The only previous control over dissociation pathways in atom-molecule collisions was demonstrated for potassium impact on gas-phase thymine and uracil. 10 By achieving controlled dissociation of purines, the present experiments show that selective reactivity in charge transfer collisions is not restricted to the particular case of pyrimidine nucleobases. Indeed, we anticipate that this new route for controlled chemistry can be adapted for numerous collision systems.…”

Interference effects in the electron and positron scattering from molecules at intermediate and high energies

“…Furthermore these damaging interactions are commonly resonant processes, such as vibrational excitation, charge transfer and electron attachment, which sometimes show selectivity and site-bond effects [4][5][6]. Examples of this behaviour were found in thymine where each of the H atoms may be selectively removed by electrons of a specific energy [7] or as a function of the electron donor kinetic energy in atom-molecule collision experiments [8]. The effective incorporation of these processes to radiation damage models would require an accurate description of all the radiation interaction sequence from the primary high energy beam until the generation of those low energy secondary species either electrons [9] or molecular radicals.…”

The role of pyrimidine and water as underlying molecular constituents for describing radiation damage in living tissue: A comparative study

“…Pyrimidine is a prototypical structure for the RNA/DNA bases thymine, cytosine, and uracil. This has made pyrimidine the subject of numerous experimental and theoretical investigations [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] that provide a near complete characterization of pyrimidine's structure and scattering cross sections. These previous findings are presented here to form a nearcomplete database for pyrimidine, including theoretical and experimental cross section data for elastic and discrete inelastic scattering and ionization and attachment processes.…”