title: The mode of binding ACMA-DNA relies on the base-pair nature.
abstract: A thermodynamic and kinetic study on the mode of binding of 9-amino-6-chloro-2-methoxi-acridine (ACMA) to poly(dA-dT)·poly(dA-dT) and poly(dG-dC)·poly(dG-dC) has been undertaken at pH = 7.0 and I = 0.1 M. The spectrophotometric, kinetic (T-jump), circular dichroism, viscometric and calorimetric information gathered point to formation of a fully intercalated ACMA complex with poly(dA-dT)·poly(dA-dT) and another one only partially intercalated (7%) with poly(dG-dC)·poly(dG-dC). The ACMA affinity with the A-T bases was higher than with the G-C bases. The two polynucleotide sequences give rise to external complexes when the ACMA concentration is raised, namely, the electrostatic complex poly(dA-dT)·poly(dA-dT)-ACMA and the major groove binding complex poly(dG-dC)·poly(dG-dC)-ACMA. A considerable quenching effect of the ACMA fluorescence is observed with poly(dA-dT)·poly(dA-dT), ascribable to face-to-face location in the intercalated A-T-ACMA base-pairs. The even stronger effect observed in the presence of poly(dG-dC)·poly(dG-dC) is related to the guanine residue from on- and off-slot ACMA positions.
authors.affiliation: Departamento de Química, Universidad de Burgos, 09001 Burgos, Spain.
authors.forename: Natalia
authors.initials: N
authors.lastname: Busto
authors.forename: Begoña
authors.initials: B
authors.lastname: García
authors.forename: José M
authors.initials: JM
authors.lastname: Leal
authors.forename: Fernando
authors.initials: F
authors.lastname: Secco
authors.forename: Marcella
authors.initials: M
authors.lastname: Venturini
mesh_terms: D000609:Aminoacridines / Q000737:chemistry*; D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D007700:Kinetics; D014783:Viscosity
chemical_list: D000609:Aminoacridines; C010847:9-amino-6-chloro-2-methoxyacridine; D004247:DNA