Copper(II) binding to tobramycin: potentiometric and spectroscopic studies.
Protonation and Cu(II) binding by tobramycin, an aminoglycosidic antibiotic, was studied by potentiometry and UV-vis, CD and EPR spectroscopies. A range of mononuclear complexes of a general formula CuHnL was found, with n between 3 and -2. Tobramycin anchors Cu(II) with an ¿NH2, O-¿ chelate of the C-ring of its molecule. The amino and hydroxyl groups of the A-ring of tobramycin also participate in the binding at pH 7 and higher. The resulting structure involves both terminal aminosugar rings but eliminates the donors of the central streptamine unit from the coordination. A comparison between tobramycin and its close analog, kanamycin B [M. Jezowska-Bojczuk, W. Bal and H. Kozłowski, Inorg. Chim. Acta, 275-276 (1998) 541-545] reveals the importance of the A3-OH group for the binding properties of these aminoglycosides.
Jezowska-Bojczuk
M
M
Faculty of Chemistry, University of Wrocław, Poland. mjb@wchuwr.chem.uni.wroc.pl
Karaczyn
A
A
Kozłowski
H
H
D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism*; D002236:Carbohydrate Conformation; D002614:Chelating Agents / Q000737:chemistry / Q000378:metabolism*; D002942:Circular Dichroism; D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D007612:Kanamycin / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D011199:Potentiometry; D011522:Protons; D014031:Tobramycin / Q000737:chemistry / Q000378:metabolism*; D014466:Ultraviolet Rays
D000900:Anti-Bacterial Agents; D002614:Chelating Agents; D011522:Protons; C001495:bekanamycin; D007612:Kanamycin; D003300:Copper; D014031:Tobramycin