Magnitude and range of the hydration pressure between lecithin bilayers as a function of headgroup density

Stalk structures in lipid bilayer fusion studied by x-ray diffraction

“…The quadratic dependence of P 0 on Ψ has been confirmed experimentally [172]. In this spirit, SIMON proposed that a common mechanism of membrane fusogens could be to increase the area per lipid and hence decrease the dipole density in the headgroup region [168]. The preferred location of Chol in a lipid bilayer has been described by the so-called umbrella model [173].…”

“…4.10 summarizes the obtained results on lipid bilayer stucture. [125,168], this indicates a simultaneous decrease of the cross-sectional area per lipid headgroup A L in the bilayer plane about the same percentage, which also reduces the number of bound water molecules per lipid [47]. A part of the work performed by application of osmotic pressure goes into bilayer deformation.…”

Magnitude of the solvation pressure depends on dipole potential.

“…For each data set, the experimental values fit quite well and three solvents are given in Table 1. Sources of experimental uncertainty of these parameters have been described elsewhere (4)(5)(6)24). Note that P0 (the value of Ph at zero bilayer separation) is larger in the gel phase than in the liquid-crystalline phase (Fig.…”

“…For phosphatidylcholine bilayers, we (4)(5)(6)24) assigned the plane of origin at the physical edge of the bilayer (Fig. 2).…”

“…The solvation pressure is thought to be the dominant interbilayer repulsive pressure for bilayer separations of about 5-20 A (1-6). For rough surfaces, such as lipid bilayers, it has been found that the solvation pressure, Ph, decays exponentially with increasing separations, such that Ph = Poexp(-df/A), where df is the distance between adjacent bilayers (1,2,(4)(5)(6) and A is the decay length. A goal of both experimentalists and theoreticians is to determine characteristics of the surface and solvents that give rise to specific values of P0 and A.…”