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Copper(II) binding to tobramycin: potentiometric and spectroscopic studies
M Jezowska-Bojczuk1, A Karaczyn, H Kozłowski
1Faculty of Chemistry, University of Wrocław, Poland. mjb@wchuwr.chem.uni.wroc.pl
Carbohydrate Research
|April 21, 1999
Summary
Tobramycin antibiotic binds Cu(II) ions through its C-ring, with A-ring groups also involved at higher pH. This binding interaction is crucial for understanding aminoglycoside antibiotic properties.
Area of Science:
- Inorganic Chemistry
- Medicinal Chemistry
- Biophysical Chemistry
Background:
- Tobramycin is an aminoglycosidic antibiotic.
- Aminoglycosides are known to chelate metal ions.
- Understanding metal binding is key to their mechanism of action and potential toxicity.
Purpose of the Study:
- To investigate the protonation and copper(II) ion binding of tobramycin.
- To characterize the structure of tobramycin-Cu(II) complexes.
- To compare binding properties with related aminoglycosides.
Main Methods:
- Potentiometry
- UV-Vis spectroscopy
- Circular Dichroism (CD) spectroscopy
- Electron Paramagnetic Resonance (EPR) spectroscopy
Main Results:
- Mononuclear Cu(II) complexes with tobramycin (CuHnL, n between 3 and -2) were identified.
- Tobramycin chelates Cu(II) via the C-ring (amine and oxygen donors).
- A-ring amino and hydroxyl groups contribute to binding at pH 7+, involving both terminal aminosugar rings.
Conclusions:
- Tobramycin's coordination to Cu(II) involves specific rings and functional groups.
- The A3-OH group is critical for binding, as shown by comparison with kanamycin B.
- Structural insights into tobramycin-metal interactions are provided.