Deuterium nuclear magnetic resonance study of water in model and biological membrane systems

A deuteron magnetic resonance study of water has been carried out in the lamellar phase of the egg yolk lecithin-water and outer membrane of E. Coli-water systems in excess water (abbreviated to EYL/EXCD₂O and EC/EXCD₂0, respectively) and egg yolk lecithin-water in 22% (by weight) water (EYL/22%WD₂0). Spectra of these systems were taken as a function of temperature, and their moments were calculated. Analysis of the integrated signal intensities revealed that the excess free (bulk) water in the EC/EXCD₂0 and EYL/EXCD₂O froze at -1°C and -2°C, respectively (pure D₂0 freezes at 4°C). The water from bilayers in the two excess water systems was frozen immediately after it was squeezed out, whereas the water squeezed out from bilayers in the EYL/22%WD₂0 remained unfrozen down to -10°C. All the squeezed out water in the EYL/22%WD₂0was frozen at -15°C. The bound water in that system was unfreezable in the region under study. The amount of water frozen out in the EYL/EXCD₂O at -2°C and in the EYL/EXCD₂O at -3°C was found to be approximately 85% of the total water content of the systems. The water frozen out in the EYL/22%WD₂0 at -15°C was determined to be 50% of the total water in that-;system. A minimum in the second moment vs temperature of the EYL/22%WD₂0 was observed and ascribed to the presence of isotropic free water squeezed out from the bilayers. Proton magnetic resonance results showed that there was no lipid phase transition in the EYL/22%WD₂0 in the region from -10°C to 48°C.Science, Faculty ofPhysics and Astronomy, Department ofGraduat