title: An ionotropic phase transition in phosphatidylcholine: cation and anion cooperativity.
abstract: Evidence is presented for cooperative interaction between cations and anions specifically bound to dimyristoylphosphatidylcholine (DMPC). The cooperativity is with regard to an ion-induced (ionotropic) phase transition for the lipid and is signalled by a change in the luminescence from bound Tb3+. The intrinsic binding of Tb3+ to DMPC was determined from equilibrium dialysis experiments, using conventional methods to correct for electrostatic contributions. Preliminary results demonstrate great potential for infrared spectroscopy as a means to relate these Tb3+ luminescence studies to experiments involving less tractable cations. This work provides insight into the role of bound ions in modifying lateral phase behavior in phospholipid membranes.
mesh_terms: D002412:Cations; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002712:Chlorides / Q000378:metabolism; D004134:Dimyristoylphosphatidylcholine / Q000378:metabolism*; D004563:Electrochemistry; D013053:Spectrophotometry; D013055:Spectrophotometry, Infrared; D013725:Terbium / Q000378:metabolism*; D013816:Thermodynamics
chemical_list: D002412:Cations; D002712:Chlorides; D013725:Terbium; D004134:Dimyristoylphosphatidylcholine