Chain length and pressure dependence of lipid translational diffusion

Abstract

The translational diffusion of pyrene, pyrene butyric acid and pyrene decanoic acid has been determined in phosphatidylcholine bilayers of different chain length and under pressure up to 200 bars. In the liquid crystalline phase and at a given temperature the diffusion decreases with increasing chain length. At a constant reduced temperature, Tred (about 10 K above the transition temperature), long chain lipids exhibit the fastest diffusion which is in disagreement with hydrodynamic models but favours free volume models for diffusion in lipid bilayers. The volume of activation, Vact, calculated from the decrease of the diffusion coefficient with pressure, delta lnD/delta P, depends on lipid chain length. Vact decreases with decreasing lipid chain length at a given temperature, T = 65 degrees C, and increases at the reduced temperature. These results are again in agreement with the dependence of the diffusion on lipid chain length and therefore with the free volume model.

Enantioselective ester hydrolysis by an achiral catalyst co-embedded with chiral amphiphiles into a vesicle membrane

“…In gel phase DSPC added amphiphiles form patches with restricted lateral movement decreasing the possibility for cooperative effects. [19][20][21] This was also previously observed by us. 18 Other membrane additives than tartrate or histidine do not show considerable effects on the relative hydrolysis rate of the enantiomeric esters.…”

Molecular Dynamics Simulations of the Lipid Bilayer Edge

“…2) is at least several times longer than for DMPC. Although the substitution of phosphatidylethanolamine for phosphatidylcholine in lipid headgroups has been shown experimentally to give to a modest decrease in probe molecule diffusion constants (Ladha et al, 1996), as have substituting longer tail tail-chains (Müller and Galla, 1987) and introducing cis-double bonds (Vaz et al, 1985), the combined effects of these substitutions would not be expected to give a 10-fold decrease in lateral diffusion constant at equilibrium. The most probable explanation for the pronounced difference in this study is that reconstruction of the edge (unlike lateral diffusion) involves a net increase in the spacing between headgroups, requiring a greater activation energy for the migration of PE headgroups (which allow hydrogen bonding between the hydrogens of the primary amine and the phosphate oxygens) than for PC headgroups.…”

Exploration of physical principles underlying lipid regular distribution: effects of pressure, temperature, and radius of curvature on E/M dips in pyrene-labeled PC/DMPC binary mixtures

“…1 (top), require a stringent structural arrangement where membrane defect or void space is not preferred. In contrast, in the irregular regions, membrane defect is more likely to occur; membrane defect creates free volume, which facilitates lipid lateral diffusion (Galla et al, 1979;Vaz and Hallmann, 1983;Peters and Beck, 1983;Muller and Galla, 1983;Vaz et al, 1985;King and Marsh, 1986;Muller and Galla, 1987). Lateral diffusion brings about collisions between pyrene moieties and, thus, an increased E/M (Birks et al, 1963).…”