title: Investigation of the interaction between thallous ions and gramicidin A in dimyristoylphosphatidylcholine vesicles: a thallium-205 NMR equilibrium study.
abstract: This study reports the first direct observation of multiple occupancy of the gramicidin A channel by Tl+ ions. 205Tl NMR has been used to study the equilibrium binding of Tl+ by gramicidin A incorporated in sonicated dimyristoylphosphatidylcholine vesicles. It is shown that only multiple-channel occupancy can account for the 205Tl chemical shifts measured. The data are analyzed to yield the equilibrium association constants of 450-600 and 5-20 M-1 for the binding of the first and the second ions at 34 degrees C, respectively.
mesh_terms: D004134:Dimyristoylphosphatidylcholine; D006096:Gramicidin; D007477:Ions; D008081:Liposomes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008954:Models, Biological; D013793:Thallium
chemical_list: D007477:Ions; D008081:Liposomes; D006096:Gramicidin; D013793:Thallium; D004134:Dimyristoylphosphatidylcholine