Resonant electron capture by uridine and deoxyuridine molecules: Fragmentation with charge transfer.

Abstract

Charge transfer via DNA plays an important role in physical and chemical processes in biological systems, and is used in biomolecular electronics. The present study considers the resonant interaction of free electrons with nucleosides, which is important for an understanding of the processes of electron transport in DNA. Resonant electron capture negative ion mass spectrometry was used to study the processes of low-energy electron attachment to two uracil nucleosides, uridine and deoxyuridine, while density functional theory (DFT) calculations were used to analyze the energy aspects of ion formation and decay. Short-lived molecular ions, formed via mechanisms of π* shape resonances, were found in the energy region below 5 eV. The fragmentation channels of these resonances and the structures of the charged and neutral products formed were determined. These results suggest that the formation of some fragment negative ions occurs through intramolecular charge transfer.