Structural features and oxidative stress towards plasmid DNA of apramycin copper complex.
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).
Balenci
D
D
Department of Chemistry, University of Siena, Via Aldo Moro, 53100 Siena, Italy.
Bonechi
G
G
D'Amelio
N
N
Gaggelli
E
E
Gaggelli
N
N
Molteni
E
E
Valensin
G
G
Szczepanik
W
W
Dziuba
M
M
Swiecicki
G
G
Jezowska-Bojczuk
M
M