title: An interaction of aminoglycoside antibiotics with Ca binding to lipid monolayers and to biomembranes.
abstract: Thirteen aminoglycoside antibiotics were investigated with respect to their ability to replace Ca from phosphatidylserine monolayers. The affinities of the glycosides for the Ca-binding sites depended on the pH and the Ca2+ concentration of the aqueous subphase. At a Ca2+ concentration of 1.2 X 10(-5)M and a pH of 7.5 the half maximum concentrations to replace Ca were found to range from 0.4 X 10(-6) (sisomicin) to 6 X 10(-6)M (streptomycin). The interaction between the streptomycins and Ca were of a competitive nature, whereas the aminoglycoside antibiotics with higher affinities displayed unusual steep dose-response curves suggesting positive cooperativity. The aminoglycoside antibiotics were also able to replace Ca from biomembranes (red cell ghosts and isolated sarcolemma of cardiac muscle) in a dose-dependent manner. The high affinity of aminoglycoside antibiotics to a phospholipid is considered to be involved in the toxic side effects of these antibiotics, e.g. nephrotoxicity and impairment of contractile force.
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001665:Binding Sites; D001667:Binding, Competitive; D002118:Calcium / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008563:Membrane Lipids / Q000378:metabolism*; D008566:Membranes / Q000378:metabolism; D008567:Membranes, Artificial; D010718:Phosphatidylserines / Q000378:metabolism
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D008563:Membrane Lipids; D008567:Membranes, Artificial; D010718:Phosphatidylserines; D002118:Calcium