TUNNELING OF PROTONS AND TAUTOMERIC TRANSITIONS IN BASE PAIRS OF DNA

Abstract

We study the interplay of the tautomeric transitions amino/keto → imino/enol of DNA base pairs and the elastic properties of the DNA, by employing the numerical simulation of the nonlinear and nonlocal Schrödinger equation that describes the concerted tunneling of protons in the hydrogen bonds of base pairs. We show that the dynamics of tunneling is characterized by solitary waves for the tunneling amplitudes. The velocity of solitons is generally small, of the order 10-3–10-2 cm/sec . We also found a phenomenon similar to the freak wave of nonlinear theory; in the context of DNA, it means that the conformation of the base pairs and the proton states, for which a tautomeric transition is only of low probability, could move along the DNA molecule and focus on a smaller set of base pairs so that the rate of transition increases. This result may have a bearing on the phenomenon of spontaneous mutations. We suggest that the irradiation of DNA with electromagnetic waves at frequencies in the infrared region, corresponding to the proton tunneling, could cause mutations.