Intensities of DNA ion-phosphate modes in the low-frequency Raman spectra.
The Raman intensities of counterion vibrations with respect to the phosphate groups of the double-helix backbone (ion-phosphate modes) in the low-frequency spectra (< 200 cm(-1)) of B -DNA with different alkali metal counterions have been calculated using the model for DNA conformational vibrations and the valence-optic approach. The results have showed that the spectra of DNA with heavy counterions (Rb(+) and Cs(+)) differ from the spectra of DNA with light counterions (Na(+) and K(+)). The calculated spectra of DNA with heavy counterions are characterized by intensive modes of ion-phosphate vibrations that form one united band near 115 cm(-1). Ion-phosphate modes in the spectra of DNA with light counterions are characterized by higher frequencies (near 180 cm(-1)) and much lower intensity. Our calculations explain why the modes of ion-phosphate vibrations are observed in Cs-DNA spectra rather than in Na-DNA. The determined sensitivity of the intensities of DNA low-frequency spectra to the counterion type proves the existence of the ion-phosphate modes.
Perepelytsya
S M
SM
Bogolyubov Institute for Theoretical Physics, NAS of Ukraine, 14-b Metrologichna St., 03680, Kiev, Ukraine. perepelytsya@bitp.kiev.ua
Volkov
S N
SN
D003198:Computer Simulation; D004247:DNA / Q000737:chemistry* / Q000648:ultrastructure*; D007477:Ions; D008956:Models, Chemical; D008958:Models, Molecular; D010710:Phosphates / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*
D007477:Ions; D010710:Phosphates; D004247:DNA