Interactions in the hydrogen belts of membranes: cholesterol leaving phosphatidylcholine bilayers.
Cholesterol transfer from sonicated liposomes of phosphatidylcholine containing 10 or 30 mole percent cholesterol was measured with erythrocytes as acceptor. The activation energies of the (rate-limiting) bilayer-cholesterol dissociation were determined. In parallel experiments, phosphatidylcholine was replaced by an analog lacking the carbonyl oxygens, diether-phosphatidylcholine. The activation energies for dissociation of cholesterol from this phospholipid were three Cal/mole smaller than those for cholesterol-phosphatidylcholine dissociation, at both concentrations of cholesterol. These results demonstrate the involvement of the carbonyl oxygen in cholesterol-phospholipid bonding and support the hypothesis of lipid-lipid hydrogen bonding in the hydrogen belts of membranes.
D000818:Animals; D002784:Cholesterol / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006860:Hydrogen Bonding; D008051:Lipid Bilayers / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism; D051381:Rats; D013816:Thermodynamics
D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; D002784:Cholesterol