Dynamics of Ion-Phosphate Lattice of DNA in Left-Handed Double Helix Form

Abstract

The conformational vibrations of Z-DNA with counterions are studied in the framework of a phenomenological model developed. The structure of a left-handed double helix with counterions neutralizing the negatively charged phosphate groups of DNA is considered as an ion-phosphate lattice. The frequencies and the Raman intensities for the modes of Z-DNA with Na+ and Mg2+ ions are calculated, and the low-frequency Raman spectra are built. At the spectral interval about the frequency 150 cm^-1; a new mode of ion-phosphate vibrations, which characterizes the vibrations of Mg2+ counterions, is found. The results of our calculations show that the intensities of Z-DNA modes are sensitive to the concentration of magnesium counterions. The obtained results describe well the experimental Raman spectra of Z-DNA.