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  • Atomic Force Microscopy and Voltammetric Investigation of Quadruplex Formation between a Triazole-Acridine Conjugate and Guanine-Containing Repeat DNA Sequences.

Atomic Force Microscopy and Voltammetric Investigation of Quadruplex Formation between a Triazole-Acridine Conjugate and Guanine-Containing Repeat DNA Sequences.

Analytical chemistry (2015-05-12)
Ana-Maria Chiorcea-Paquim, Ana Dora Rodrigues Pontinha, Ramon Eritja, Genny Lucarelli, Silvia Sparapani, Stephen Neidle, Ana Maria Oliveira-Brett
ABSTRACT

The interactions of the Tetrahymena telomeric repeat sequence d(TG4T) and the polyguanylic acid (poly(G)) sequence with the quadruplex-targeting triazole-linked acridine ligand GL15 were investigated using atomic force microscopy (AFM) at a highly oriented pyrolytic graphite and voltammetry at a glassy carbon electrode. GL15 interacted with both sequences, in a time dependent manner, and G-quadruplex formation was detected. AFM showed the adsorption of quadruplexes as small d(TG4T) and poly(G) spherical aggregates and large quadruplex-based poly(G) assemblies, and voltammetry showed the decrease and disappearance of GL15 and guanine oxidation peak currents and appearance of the G-quadruplex oxidation peak. The GL15 molecule strongly stabilized and accelerated G-quadruplex formation in both Na(+) and K(+) ion-containing solution, although only K(+) promoted the formation of perfectly aligned tetra-molecular G-quadruplexes. The small-molecule complex with the d(TG4T) quadruplex is discrete and approximately globular, whereas the G-quadruplex complex with poly(G) is formed at a number of points along the length of the polynucleotide, analogous to beads on a string.

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