Theoretical studies of the kinetics, thermochemistry, and mechanism of hydrogen-abstraction from methanol and ethanol

Brownian dynamics simulations of the reactions of hydrated electrons with components of DNAs and a DNA double-helix

“…This makes the Brownian dynamics simulation model simpler. On the other hand, the attack of the sugar moieties and the bases by the hydroxyl radicals are not likely to be strictly diffusion-limited 13 , as also suggested by quantum calculations 12 that the activation barriers for the addition of radicals to the bases and the hydrogen abstraction from the sugars by the radicals are non-negligible. A proper theoretical understanding and prediction of the reaction rate constants will therefore require an integrated study of both the relative diffusion between DNAs and DNAdamaging agents, and the subsequent reactions that take place.…”

“…These radicals are responsible for most of the strand breaks in the indirect mechanism of radiation damage 10,11 . Quantum chemical methods have already been used to estimate the activation barriers for the abstraction of hydrogens from the sugar moieties of DNAs by hydroxyl radicals 12 . The purpose of the Brownian dynamics simulations presented here is to develop and evaluate simulation models that can be integrated with results from quantum chemical calculations to quantify the rate constants of the reaction of hydroxyl and hydrogen radicals with DNAs, and to predict the probability that these radicals attack different sites of the DNAs.…”

Quantitative determination of the selectivities of five different phenyl radicals in hydrogen atom abstraction from ethanol

“…The experimental determination of the selectivities of five charged phenyl radicals toward the three different types of hydrogen atoms in unlabeled ethanol indicate that, like HO⅐ radical [7,19], there is a strong preference for H-atom abstraction from the CH 2 -group in ethanol by all of the phenyl radicals. In addition, the preference (selectivity) for the CH 2 -group increases and that for the CH 3 -group decreases as the reactivity (and electrophilicity) of the phenyl radical decreases.…”

“…This experimental method involves studying the reactivities and selectivities of derivatives of the radicals that contain a chemically inert, charged group (distonic ions), which allows them to be manipulated in a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer. A large number of studies suggest that the action of some potential anti-tumor antibiotics is based on H-atom abstraction by aromatic, ,-biradical intermediates from a sugar moiety in DNA (which ultimately leads to cell death) [1][2][3][4][5][6][7][8][9]. These compounds, however, are also destructive to healthy cells.…”

A quantum mechanical approach to the kinetics of the hydrogen abstraction reaction H2O2 + •OH → HO2 + H2O

“…Among the one-dimensional methods are Wigner and Eckart's unsymmetric barrier methods [12,13]. The Eckart potential energy barrier goes through the zero-point corrected energies at the reactants, transition states, and products [14], while the Wigner tunneling correction only needs the imaginary frequency which determines the motion along the minimum energy path (MEP) from the transition state to both reactants and products.…”