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Dissociative electron attachment to the gas-phase nucleobase hypoxanthine

journal contribution
posted on 2024-11-07, 20:02 authored by M. M. Dawley, K. Tanzer, I. Carmichael, S. Denifl, S. Ptasinska
We present high-resolution measurements of the dissociative electron attachment (DEA) to isolated gas-phase hypoxanthine (C5H4N4O, Hyp), a tRNA purine base. The anion mass spectra and individual ion efficiency curves from Hyp were measured as a function of electron energy below 9 eV. The mass spectra at 1 and 6 eV exhibit the highest anion yields, indicating possible common precursor ions that decay into the detectable anionic fragments. The (Hyp − H) anion (C5H3N4O−) exhibits a sharp resonant peak at 1 eV, which we tentatively assign to a dipole-bound state of the keto-N1H,N9H tautomer in which dehydrogenation occurs at either the N1 or N9 position based upon our quantum chemical computations (B3LYP/6-311+G(d,p) and U(MP2-aug-cc-pVDZ+)) and prior studies with adenine. This closed-shell dehydrogenated anion is the dominant fragment formed upon electron attachment, as with other nucleobases. Seven other anions were also observed including (Hyp − NH)−, C4H3N4−/C4HN3O−, C4H2N3−, C3NO−/HC(HCN)CN−, OCN−, CN−, and O−. Most of these anions exhibit broad but weak resonances between 4 and 8 eV similar to many analogous anions from adenine. The DEA to Hyp involves significant fragmentation, which is relevant to understanding radiation damage of biomolecules.

History

Temporal Coverage

2015

Extent

Page 21501

Publisher

J. Chem. Phys.

Source

Volume 142

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    Radiation Laboratory

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