Proton Transfer in Adenine−Thymine Radical Cation Embedded in B-Form DNA

On the basis of pKa measurements, it has been predicted that proton transfer will not occur in the radical cation of the A/T base pair (A: adenine, T: thymine). Testing this prediction, we have performed simulations as a function of time on an A/T oligomer missing one electron, in solution, using the code CP2K. We find that proton transfer occurs rapidly at temperatures below room temperature. We suggest that the difference in behavior of (A/T)·+ from that predicted on the basis of pKa measurements is the effect of hydration. Hydration also appears to have effects not previously considered on hole motion in solution.