Supramolecular Guanosine 5‘-Monophosphate Structures in Solution. Light Scattering Study

Abstract

During the past decade, from the vast evidence it became clear that DNA oligomers rich in guanine stretches can form in solution highly ordered forms called G-quadruplexes and G-wires. G-quadruplexes are present in many sites of the human genome, can inhibit telomerase, and can be used as drug delivery supramolecules. G-wires and related structures seem to be an excellent material of biological origin for nanostructures. Therefore, in this paper we have studied the structures formed by specific association of guanosine 5′-monophosphate (GMP) nucleotide molecules in water solutions by photon correlation spectroscopy and depolarized Rayleigh light scattering. One relaxation process with distinct amplitude was observed, as a function of temperature and sample concentration. It was attributed to the translational diffusion coefficient of the stacks of G-quartets in a range of high concentration and to the stacks of GMP monomer associates for low concentration (less than 40 mg/mL). From the measurements the hydrodynamic radius of GMP molecule has been estimated as rH = 5.4 A. The bead modeling of the hydrodynamic parameters allowed us to distinguish the wide spectrum of structures formed in solution: from single GMP nucleotides to stacks of multiassociates of G-quartets of GMP.