engleski

Influence of magnesium ions on the structure of DNA investigated by FTIR spectroscopy

Influence of magnesium ions on the structure of DNA investigated by FTIR spectroscopy K. Serec1, S. Dolanski Babić1 , S. Tomić2 1School of Medicine, University of Zagreb, Croatia, 2Institut za fiziku, Zagreb Corresponding author e-mail: kristinaserec@gmail.com Previous research showed that under influence of Mg+2 cations DNA undergoes structural and conformational changes [1-6]. It was pointed out by many authors that regardless of the conditions, Mg ions show great affinity toward phosphate groups of DNA, thus neutralizing and stabilizing double helical structure. Interaction of the Mg ions with the base sites, however, still remains unclear as different authors report different affinities and preferable sites of Mg-base coordination [1, 2, 5, 6]. Thus, possibility and particular mechanism of Mg-DNA interaction still remains unclear, as experimental data is often not consistent. In order of finding the best model, we developed protocols where Mg-DNA interaction can be tested with and without intrinsic Na cations, and over large interval of molar concentrations ratio (r=[Mg2+]/[P]). Fourier Transform Infrared spectroscopy was used to determine the effects of Mg2+ ions on the structure and conformation of DNA in thin films. Since DNA is highly sensitive to quantity of metal ions, samples were prepared in such a way as to have r over 4 orders of magnitude (r= 0.0067 to 30). Also, in order to eliminate/determine influence of sodium ions extensive dialysis was performed, and then compared with samples containing sodium ions. References 1. Bhattacharyya, R.G., K.K. Nayak, and A.N. Chakrabarty, Interaction of Mgatp2- with DNA - Assessment of Metal-Binding Sites and DNA Conformations by Spectroscopic and Thermal-Denaturation Studies. Inorganica Chimica Acta-Bioinorganic Chemistry, 1988. 153(2): p. 79-86. 2. Langlais, M., H.A. Tajmirriahi, and R. Savoie, Raman-Spectroscopic Study of the Effects of Ca-2+, Mg-2+, Zn-2+, and Cd-2+ Ions on Calf Thymus DNA - Binding-Sites and Conformational-Changes. Biopolymers, 1990. 30(7-8): p. 743-752. 3. Duguid, J., et al., Raman Spectral Studies of Nucleic-Acids .44. Raman-Spectroscopy of DNA-Metal Complexes .1. Interactions and Conformational Effects of the Divalent-Cations - Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Pd, and Cd. Biophysical Journal, 1993. 65(5): p. 1916-1928. 4. Duguid, J.G., et al., Raman spectroscopy of DNA-Metal complexes .2. The thermal denaturation of DNA in the presence of Sr2+, Ba2+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, and Cd2+. Biophysical Journal, 1995. 69(6): p. 2623-2641. 5. Hackl, E.V., S.V. Kornilova, and Y.P. Blagoi, DNA structural transitions induced by divalent metal ions in aqueous solutions. International Journal of Biological Macromolecules, 2005. 35(3-4): p. 175-191. 6. Ahmad, R., H. Arakawa, and H.A. Tajmir-Riahi, A Comparative Study of DNA Complexation with Mg(II) and Ca(II) in Aqueous Solution: Major and Minor Grooves Bindings. Biophysical Journal, 2003. 84(4): p. 2460-2466.

DNA; magnesium cations; infrared spectroscopy

nije evidentirano