Low-frequency dynamics of DNA in Brillouin light scattering spectra

Brillouin light scattering studies of deoxyribonucleic acid (DNA) in the temperature interval $297$–$375$ K are presented. DNA fragment ($119$ bp) from the 1st intron of $D$ melanogaster limk1 gene with AT-rich insertion ($28$ bp, mutant $agn^{ts3}$) was used as an experimental sample. The temperature dependence of the hypersound velocity was found to exhibit anomalies in the vicinity of $347$ and $335$ К. Computer modeling of possible conformational states which might be attained by the DNA fragment under study has shown the existence of local structures that evolve with varying temperature. Combined analysis of experimental data and results of the modeling reveals a close relation between the anomalous behavior of Brillouin light scattering spectra and conformational DNA dynamics. The results are discussed in the framework of modern models of conformational DNA transformations.