Guanosine + OH radical reaction in aqueous solution: a reinterpretation of the UV-vis data based on thermodynamic and kinetic calculations.

Thermodynamic and kinetic calculations have been used to reinterpret the UV-vis data related to the OH radical oxidation of guanosine. The main channel of reaction (70-75%) is proposed to be the formation of a guanosine radical cation followed by deprotonation. It accounts for both the absorbance decay at approximately 620 nm and the build-up at approximately 300 nm. A secondary channel yielding the G8OH adduct was found to contribute to the overall reaction by 12% at least.