title: Structural features and oxidative stress towards plasmid DNA of apramycin copper complex.
abstract: The interaction of apramycin with copper at different pH values was investigated by potentiometric titrations and EPR, UV-vis and CD spectroscopic techniques. The Cu(II)-apramycin complex prevailing at pH 6.5 was further characterized by NMR spectroscopy. Metal-proton distances derived from paramagnetic relaxation enhancements were used as restraints in a conformational search procedure in order to define the structure of the complex. Longitudinal relaxation rates were measured with the IR-COSY pulse sequence, thus solving the problems due to signal overlap. At pH 6.5 apramycin binds copper(II) with a 2 : 1 stoichiometry, through the vicinal hydroxyl and deprotonated amino groups of ring III. Plasmid DNA electrophoresis showed that the Cu(II)-apramycin complex is more active than free Cu(II) in generating strand breakages. Interestingly, this complex in the presence of ascorbic acid damages DNA with a higher yield than in the presence of H(2)O(2).
authors.affiliation: Department of Chemistry, University of Siena, Via Aldo Moro, 53100 Siena, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Balenci
authors.forename: G
authors.initials: G
authors.lastname: Bonechi
authors.forename: N
authors.initials: N
authors.lastname: D'Amelio
authors.forename: E
authors.initials: E
authors.lastname: Gaggelli
authors.forename: N
authors.initials: N
authors.lastname: Gaggelli
authors.forename: E
authors.initials: E
authors.lastname: Molteni
authors.forename: G
authors.initials: G
authors.lastname: Valensin
authors.forename: W
authors.initials: W
authors.lastname: Szczepanik
authors.forename: M
authors.initials: M
authors.lastname: Dziuba
authors.forename: G
authors.initials: G
authors.lastname: Swiecicki
authors.forename: M
authors.initials: M
authors.lastname: Jezowska-Bojczuk