Eur. Phys. J. E (2004) 13: 27-33
https://doi.org/10.1140/epje/e2004-00037-0

Dynamic light scattering and ³¹P NMR study of the self-assembly of deoxyguanosine 5’-monophosphate: the effect of added salt

¹ Faculty of Mechanical Engineering, University of Maribor, Smetanova 17, 2000, Maribor, Slovenia
² Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia
³ Jozef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
⁴ Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, 1000, Ljubljana, Slovenia
⁵ Istituto di Scienze Fisiche, Facoltá di Medicina e Chirurgia, Universitá di Ancona, and INFM, via Ranieri 65, 60131, Ancona, Italy

^* e-mail: lea.spindler@uni-mb.si

Abstract

Self-assembling and dynamical properties of deoxyguanosine 5’-monophosphate in isotropic aqueous solutions were studied by ³¹P NMR spectroscopy and dynamic light scattering (DLS). All solutions had the same c = 4 wt% guanosine concentration, while the added KCl molarity ranged from 0 to 1.5 M. ³¹P NMR measurements show that potassium ions strongly enhance the stacking process of guanosine tetramers until a saturation is reached at 0.1 M KCl with more than 70% of the molecules aggregated. Polarized light scattering reveals the presence of a fast relaxation mode that arises from the translational dynamics of the self-assembled stacks. The diffusion coefficient of this mode shows a strong dependence on molarity of added salt, which can be described in terms of the coupled mode and counterion condensation theories for polyelectrolyte solutions. Depolarized light scattering reveals the rotational dynamics of the self-assembled stacks which exhibits a pronounced slowing down with increasing the added salt content.