Modeling Radical Yields in Oriented DNA Exposed to High-LET (Linear-Energy-Transfer) Radiation

摘要

Monte Carlo simulation of energy absorption in oriented fibers of DNA is used to model the dependence of free radical yields on the orientation of the fibers relative to a flux of ionizing radiation. A large asymmetry was assumed in the thermal conductivity of the fibers that permits rapid transport of vibrational energy along a DNA molecule, but not between different molecules. Based on this assumption, the model predicts that thymine radical anions have a significantly greater probability of undergoing a secondary protonation reaction if they are produced by a flux that is incident perpendicular to the DNA molecules. These results are in qualitative agreement with experimental data on the yield of 5,6-dihydrothymin-5-yl radicals when samples of oriented DNA were exposed at 77 K to neutrons. Keywords: High linear energy transfer, LET (Linear energy transfer), High energy protons, Reprints. (aw)