title: Atomic Force Microscopy and Voltammetric Investigation of Quadruplex Formation between a Triazole-Acridine Conjugate and Guanine-Containing Repeat DNA Sequences.
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.
authors.affiliation: †Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Chiorcea-Paquim
authors.affiliation: †Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
authors.forename: Ana Dora Rodrigues
authors.initials: AD
authors.lastname: Pontinha
authors.affiliation: ‡Institute for Research in Biomedicine, IQAC-CSIC, CIBER-BBN Networking Centre on Bioengineering, Biomaterials and Nanomedicine, Barcelona, Spain.
authors.forename: Ramon
authors.initials: R
authors.lastname: Eritja
authors.affiliation: §UCL School of Pharmacy, University College London, London WC1N 1AX, U.K.
authors.forename: Genny
authors.initials: G
authors.lastname: Lucarelli
authors.affiliation: §UCL School of Pharmacy, University College London, London WC1N 1AX, U.K.
authors.forename: Silvia
authors.initials: S
authors.lastname: Sparapani
authors.affiliation: §UCL School of Pharmacy, University College London, London WC1N 1AX, U.K.
authors.forename: Stephen
authors.initials: S
authors.lastname: Neidle
authors.affiliation: †Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Oliveira-Brett
mesh_terms: D000166:Acridines / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D055664:Electrochemical Techniques; D054856:G-Quadruplexes; D006147:Guanine / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D015394:Molecular Structure; D012091:Repetitive Sequences, Nucleic Acid; D014230:Triazoles / Q000737:chemistry*
chemical_list: D000166:Acridines; D014230:Triazoles; D006147:Guanine; D004247:DNA