Electron Attachment to the Nucleobase Uracil in Diethylene Glycol: The Signature of a Doorway.

The cellular environment plays a significant role in low energy electron-mediated radiation damage to genetic materials. In this study, we have modeled the effect of the bulk medium on electron attachment to nucleobases in diethylene glycol (DEG) using uracil as a test case, in accordance with recent experimental work on the observation of dissociative quasi-free electron attachment to nucleoside via excited anion radical in solution (in DEG). Our EOM-CCSD-based quantum mechanical/molecular mechanical (QM/MM) simulations indicate that the electron scavenging by uracil in DEG is much slower than that observed in the aqueous medium due to its viscosity.

Secondary Electron Attachment-Induced Radiation Damage to Genetic Materials.

Reactions of radiation-produced secondary electrons (SEs) with biomacromolecules (e.g., DNA) are considered one of the primary causes of radiation-induced cell death.

Electron Attachment to DNA: The Protective Role of Amino Acids.

We have studied the effect of amino acids on the electron attachment properties of a DNA nucleobase, with cytosine as a model system. The equation of motion coupled cluster theory with an extended basis set has been used to simulate the electron-attached state of the DNA model system. Arginine, alanine, lysine, and glycine are the four amino acids considered to investigate their role in electron attachment to a DNA nucleobase.

Five-membered N-heterocyclic beryllium(I) compounds: fluctuating electronic structures with ambiphilic reactivity.

The structure, bonding, and reactivity of the five-membered N-heterocyclic beryllium compounds (NHBe), BeNCH (1) and BeN(CH)CH (2) were studied at the M06/def2-TZVPP//BP86/def2-TZVPP level of theory. The molecular orbital analysis indicates that NHBe is an aromatic 6π-electron system with an unoccupied σ-type sp-hybrid orbital on Be. Energy decomposition analysis combined with natural orbitals for chemical valence has been carried out with Be and L (L = NCH (1), N(CH)CH (2)) in their different electronic states as fragments at the BP86/TZ2P level of theory.

Electron Attachment to Wobble Base Pairs.

We have analyzed the low-energy electron attachment to wobble base pairs using the equation of motion coupled cluster method and extended basis sets. A doorway mechanism exists for the attachment of the additional electron to the base pairs, where the initially formed dipole-bound anion captures the incoming electron. The doorway dipole-bound anionic state subsequently leads to the formation of a valence-bound state, and the transfer of extra electron occurs by mixing of electronic and nuclear degrees of freedom.

Doorway Mechanism for Electron Attachment Induced DNA Strand Breaks.

We report a new doorway mechanism for the dissociative electron attachment to genetic materials. The dipole-bound state of the nucleotide anion acts as the doorway for electron capture in the genetic material. The electron gets subsequently transferred to a dissociative σ*-type anionic state localized on a sugar-phosphate or a sugar-nucleobase bond, leading to their cleavage.