Reactions of water-soluble alkylperoxyl radicals and superoxide with DNA, lipoproteins and phospholipid vesicles: the role played by electrostatic forces.

The role of electrostatic forces in free radical biology is very important but it is all too often overlooked. The radicals discussed in this review include positively-charged, negatively-charged and neutral water-soluble alkylperoxyls and superoxide. Important scientific insights have been gained by generating these radicals in known quantities by the thermal decomposition of simple, "clean", chemical precursors in the presence of potential bio-targets. For example, the abilities of these radicals to damage double-stranded DNA, a polyanion, are dictated by Coulombic forces with only the positively-charged peroxyls being capable of directly producing single-strand breaks. The Coulombic control of the reactions and reaction rates of water-soluble peroxyl radicals which are so evident with DNA do not manifest themselves with all electrostatically charged bio-targets, e.g., low density lipoprotein (LDL), probably because the charge on the surface of the LDL is not uniformly distributed.