Radiation-induced structural modifications in dsDNA analysed by FT-Raman spectroscopy

Abstract

Structural changes of double stranded DNA in aqueous solution induced by ionizing radiation were studied by Fourier-Transform-Raman spectroscopy. In addition to base damage, strand breaks, structural changes, i.e. unstacking of the bases, premelting effects and disordering of the B-form backbone could be observed. The amount of these different kinds of damage depended on the concentration of the DNA solution. Specifically, the following modifications were found depending on the gamma-ray dose and DNA concentration. (1) Intensity increase of the lines of dT (1240 cm-1) and dA (729, cm-1) indicating unstacking of these bases. (2) Intensity and frequency changes of the marker bands of all four bases indicating structural modifications. (3) Intensity decrease of the sugar marker lines showing change of the bonds in the deoxyribose and of bonds between the sugar moiety and the phosphodiester. (4) Intensity decrease of the lines of the phosphodiester groups (1094 and 790 cm-1) with simultaneous appearance of a difference peak at 1080 cm-1 and a new peak at 980 cm-1 suggesting the presence of strand breaks. (5) Intensity decrease of the B-form marker band (approximately 835 cm-1) and new lines at 876 cm-1), at approximately 660 cm-1 (C3'-endo/anti of dG) and at 1312 cm-1 (C3'endo/syn of dA) indicating decrease of the B-form conformation and the developing of partly new secondary forms of the DNA representing a helix-to-coil transition.

Molecular Spectroscopic Markers of DNA Damage

“…Synytsya et al applied Raman spectroscopy to evaluate specific dose-dependent alterations in the double stranded DNA (dsDNA) molecules of calf thymus, following proton and γ-irradiation (0.5-50 Gy) in dilute aqueous solutions of DNA [13]. A decrease in the intensity of the ribose deformational vibration shoulders at 1460 and 1418 cm −1 , as well as the appearance of new features of terminal phosphates at 1077-1087 cm −1 , and 982-985 cm −1 , can be used as markers of SSBs or DSBs in dsDNA, arising due to irradiation [38]. Sailer et al studied structural changes in dsDNA in aqueous solution, induced by γ-radiation, using Fourier-Transform-Raman spectroscopy.…”

Spectroscopic and chemometric approaches to radiobiological analyses

“…The increased resolution in CRM imaging has also been exploited to enable the detection of cellular mitochondrial distribution [44] and phagosomes [45]. Early applications of both techniques in radiobiology had focussed on studies with Raman spectroscopy of radiation-induced peroxidation in model phospholipid and membrane systems [46,47], structural changes in protein [48] and in nucleic acids [49]. Such studies continue to contribute to the understanding of the interaction mechanisms between radiation and key molecular species and structures within the cell [48][49][50][51].…”

“…Early applications of both techniques in radiobiology had focussed on studies with Raman spectroscopy of radiation-induced peroxidation in model phospholipid and membrane systems [46,47], structural changes in protein [48] and in nucleic acids [49]. Such studies continue to contribute to the understanding of the interaction mechanisms between radiation and key molecular species and structures within the cell [48][49][50][51]. These investigations have since evolved to Raman spectroscopic studies of the effects of in-vitro proton irradiation of excised tissues [52], and radiotherapeutically irradiated (γ-radiation) tissue specimens [53][54][55].…”

A synchrotron-based infrared microspectroscopy study on the cellular response induced by gold nanoparticles combined with X-ray irradiations on F98 and U87-MG glioma cell lines

“…47 The increase in the intensity of the DNA backbone was correlated with multiple DNA breakages. 47,50 When comparing NP-treated cells in the lipid region (3100-2800 cm −1 ), the score plots do not display clear separated clusters, despite the fact that the NP-treated groups at T 24h seem to be slightly separated towards positive PC-1 in both cell lines from the other groups (T 0h and T 24h without AuNP). Fig.…”