1. Structural features and oxidative stress towards plasmid DNA of apramycin copper complex.
- Author
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Balenci, D., Bonechi, G., D'Amelio, N., Gaggelli, E., Gaggelli, N., Molteni, E., Valensin, G., Szczepanik, W. W., Dziuba, M., Święcickib, G., and Jeżowska-Bojczuk, M.
- Subjects
MOLECULAR structure ,OXIDATIVE stress ,PLASMIDS ,DNA ,COPPER compounds ,METAL complexes ,HYDROGEN-ion concentration ,NUCLEAR magnetic resonance spectroscopy - 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 O2 . [ABSTRACT FROM AUTHOR]- Published
- 2009
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