ORDER AND MEMBRANE STABILITY FROM MAGNETIC-RESONANCE MEASUREMENTS - AN APPLICATION OF STATISTICAL THERMODYNAMICS

This paper compares different approaches, reported in the literature, for obtaining thermodynamic statistical information from ESR and NMR measurements on the conformations of lipid bilayers. A statistical approach recently proposed by the authors has been employed to reexamine several literature values of order parameters and to calculate Helmholtz free energy and entropy. This approach was applied to eggphosphatidylcholine, cerebroside and gangliosoyds, spin labelled at different acyl chain positions, and to bilayered membranes containing phosphatidylcholine and different gangliosides (GM1, GD1a and GT1b) at increasing glycolipid mole percent. The variation of the stability of the membrane with the peroxidation is also reexamined at different intramembrane locations by various probes.