Thermally induced shape fluctuations of giant quasi-spherical lipid vesicles are used to study the bending elasticity modulus kc of a phospholipid membranes in presence of beta 2 glycoprotein I in the aqueous solution which surrounds the vesicle's membrane. The bending elastic modulus kc of phospholipid membrane was obtained for different concentrations of beta 2 glycoprotein I for pure neutral SOPC membranes and for mixed SOPC: Cardiolipin negatively charged membranes. The experimental results for the bending elastic modulus kc of the phospholipid membranes does not show dependence on the concentration of β2-GPI in the range from 5.5 to 55 μg/ml.
COBISS.SI-ID: 8651860
We present experimental and theoretical results which concern the deviations from circularity of the pivotal plane in the inverse hexagonal phases (HII) of phospholipid self-assemblies. Due to packing constraints, the cross-section of the polar/apolar interface deviates from a circle, which we studied in minute detail by analysing small-angle X-ray diffraction data of DOPE and SOPE, respectively. On this structural basis, Monte Carlo simulated annealing variations of the free energy were carried out, both on the formation of the HII-phase. The equilibrium of the HII-phase pivotal plane contour and the corresponding values of the mean intrinsic curvature, and the hydrocarbon chain stiffness, were determined from MC calculations. The results of these calculations were tested by solving the corresponding system of non-linear differential equations derived using variational calculus.
COBISS.SI-ID: 8208468