Monolayer interactions of phospholipids and cholesterol

Abstract

SUMMARYI. The force-area characteristics of monolayers of saturated and unsaturated phospholipids have been studied.2. Interaction in phospholipid monolayers depends on the nature of the fatty acid constituents of the phospholipid, and on the temperature.3. The mean area per molecule in mixed films of cholesterol with (I,2-distearoyl)-3-lecithin and (I,2-didecanoyl)-3-1ecithin at 22 ° practically followed the simple additivity rule.4-A condensing effect of cholesterol was evident with films of (I-stearoyl-2-lauroyl)-3-1ecithin; (I,2-ditetradecanoyl)-3-1ecithin, (I-stearoyl-2-oleoyl)-3-1ecithin and the corresponding ethanolamine analogue, as well as with (I,2-dioleoyl)-3-1ecithin at 22 °. At 5 ° the condensation effect with (I,2-ditetradecanoyl)-3-1ecithin was much reduced.5. The very expanded films of synthetic lecithins and phosphatidyl ethanolamines containing linoleic and linolenic acid showed no appreciable condensation effects with cholesterol.6. The behaviour of the mixed cholesterol-phospholipid films is governed by a number of factors, including Van der Waals' interactions, configurational entropy effects and alterations in the structure of water adjacent to the monolayers. These factors depend on chain length and degree of unsaturation.

The effect of the sterol oxygen function on the interaction with phospholipids

“…A strong condensing effect is demonstrated, plotting the mole fraction of sterol against the mean molecular area, and a strong deviation from ideal behaviour is found at all surface pressures. At 50 mol% cholesteryl methyl ether and a surface pressure of 5 or 20 mN • ml 1, the reduction in mean molecular area is 10.5 and 9.5 A2.mol-l, respectively (Table II), which is slightly less than obtained for cholesterol in a mixed film with oleoylstearoylphosphatidylcholine [1,14].…”

“…Many studies have demonstrated that sterols greatly affect the barrier properties of membranes. Monolayer studies have demonstrated a so-called condensing effect [1][2][3], this is a decrease in mean molecular area in mixtures of phospholipid and cholesterol. The increase in chain order in the liquid-crystalline state leads to a decreased permeability [4,5].…”

Membrane fluidity, cholesterol and allosteric transitions of membrane‐bound Mg2+‐ATPase, (Na+ + K+)‐ATPase and acetylcholinesterase from rat erythrocytes

“…A high cholesterol-phospholipids molar ratio of about 0.8 is found in rat erythrocytes [ 17] and unpublished results}. It is known that cholesterol interacts with erythrocyte phospholipids reducing its molecular area [ 18,19]. Electron spin resonance studies indicate that these interactions cause a diminution in the local fluidity of the lipid matrix of the erythrocyte membrane [2].…”

The interaction energies of cholesterol and lecithin in spread mixed monolayers at the air-water interface

“…The pressure-area curves of dilauroyl lecithin, diundecyloyl lecithin dinonanoyl lecithin and dioctanoyl lecithin, as well as dimyristoyl lecithin and didecanoyl lecithin (reproduced from ref. 8), are shown in Fig. 2.…”