Open AccessThe Interactions between Monovalent Ions and Phosphatidyl Cholines in Aqueous Bilayers
Author(s) -
SÖDERMAN Olle,
ARVIDSON Gösta,
LINDBLOM Göran,
FONTELL Krister
Publication year - 1983
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1983.tb07567.x
Subject(s) - chemistry , bilayer , aqueous solution , ion , lamellar structure , lipid bilayer , phosphatidylcholine , membrane , salt (chemistry) , molecule , crystallography , chemical physics , organic chemistry , phospholipid , biochemistry
The interactions of lithium and sodium ions and water with phosphatidylcholine bilayers have been studied by means of 7 Li, 23 Na and 2 H NMR quadrupole splittings. The experimental results are interpreted in terms of a simple three‐site model with two anisotropic sites (‘binding’ sites) and one isotropic site (‘free’ ions and water molecules). The findings obtained for the zwitterionic model membrane are compared with previous investigations of lamellar phases composed of ionic and nonionic amphiphiles. It is shown that the data obtained are compatible with our previous suggestion [Lindblom, G., Persson, N.‐O., and Arvidson G. (1976) Adv. Chem. Ser. 152 , 121] that an increase in the salt content in the water layer induces a conformational change in the polar head group of phosphatidylcholine. Thus at high salt concentration the phosphocholine head group tends to be oriented perpendicular to the lipid bilayer surface. The study also shows that increasing the amount of salt leads to a squeezing out of water between the bilayers. This is interpreted in terms of a reduction of the repulsion forces between the bilayers.