Beat motion in DNA double helix and a mechanism of energy exchange between its two strands with microwave frequency Original Research Article

A linear vibration theory of base rotation for the B-form DNA double helix is proposed in terms of a new Hamiltonian in which, in addition to the hydrogen-bond energy, the dipole-dipole interaction between two bases in a base pair is taken into account. The H-bond energy takes the general form and is expanded in terms of a Taylor series. In an important case in which the vibration amplitude is small, a set of coupled Klein-Gordon equations has been derived. The solution of the equations under some initial and boundary conditions shows that a special motion form, the beat motion, occurs between the bases and their complementary bases. According to the beat motion, the energy flows back and forth between the bases and their complementary bases. The value of the beat frequency strongly depends on the dipole moments of the bases. In the case of Poly(dG)-Poly(dC), the beat frequency is estimated to be about 2 GHz, i.e., in the range of microwaves. The precise value of the beat frequency depends on the vibration modes, the length and the shape (linear or circular) of the DNA chain. It is shown that the phenomenon of beat is mainly caused by the dipole-dipole interaction. The resonant absorption of the microwave energy and the possible biological implication of the beat motion have been discussed. However, further experimental confirmation is needed before any major advances can be made.