Anion influence on the binding of divalent cations to phosphatidylcholine.
We have used the osmotic pressure technique of Rand, Parsegian and co-workers (Nature 259 (1976) 601-603) to investigate the effect of anion species on the binding of M2+ to dipalmitoylphosphatidylcholine bilayers. Calcium and magnesium salts show a complex behavior which is consistent with both anion binding and screening. We observe virtually no change, within the accuracy of our experiment, in the decay of repulsive pressure with inter-bilayer separation for the acetate and nitrate salts of magnesium and calcium; however, the chloride salt does show a different pressure decay. At any given bilayer separation, 35 A less than dw less than 75 A, with calcium and magnesium salts present, the anions produce a decrease in the repulsive pressure in the order acetate- greater than Cl- greater than NO-3.
D000838:Anions; D002118:Calcium; D002413:Cations, Divalent; D008051:Lipid Bilayers; D008274:Magnesium; D009997:Osmotic Pressure; D011663:Pulmonary Surfactants; D013499:Surface Properties
D000838:Anions; D002413:Cations, Divalent; D008051:Lipid Bilayers; D011663:Pulmonary Surfactants; D008274:Magnesium; D002118:Calcium