title: Quadruplex nanostructures of d(TGGGGT): influence of sodium and potassium ions.
abstract: The Tetrahymena telomeric repeat sequence d(TG4T) contains only guanine (G) and thymine (T) bases and has medical and nanotechnological applications because of its ability to self-assemble into stiff tetra-molecular parallel-stranded G-quadruplexes. The hexadeoxynucleotide d(TG4T) was studied using atomic force microscopy (AFM) on the highly oriented pyrolytic graphite surface and differential pulse (DP) voltammetry at a glassy carbon electrode. The d(TG4T) single-strands self-assembled into G-quadruplex structures, very fast in K(+) ions solution and slowly in Na(+) ions containing solution. The G-quadruplex structures were detected in AFM by the adsorption of small spherical aggregates and by DP voltammetry by the G oxidation peak decrease and G-quartets oxidation peak occurrence, in a time and K(+) ions concentration dependent manner. In the presence of Na(+) ions, the d(TG4T) single-strands also slowly self-assembled into higher-order nanostructures, detected by AFM as short nanowires and nanostructured films that were never observed in K(+) ions containing solution.
authors.affiliation: Department of Chemistry, University of Coimbra , 3004-535 Coimbra, Portugal.
authors.forename: Ana Dora
authors.initials: AD
authors.lastname: Rodrigues Pontinha
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Chiorcea-Paquim
authors.forename: Ramon
authors.initials: R
authors.lastname: Eritja
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Oliveira-Brett
mesh_terms: D054856:G-Quadruplexes; D018625:Microscopy, Atomic Force; D049329:Nanostructures; D011188:Potassium / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry*
chemical_list: D012964:Sodium; D011188:Potassium