Direct Determination of Hydration in the Lamellar to Inverted Hexagonal Transition of Phosphatidylethanolamine

摘要

The bound water associated with Phosphatidylethanolamine (PtdEtn) in the lamellar end inverted hexagonal structures is determined directly. Bound water is considered as that water which is unavailable for solvation of the polar solute sucrose. In the fluid lamellar (L_α) state of dioleoyl PtdEtn (at 2 deg C), 7.2 water molecules per phospholipid are bound and unavailable as a solvent for sucrose. In the inverted hexagonal structure (16 deg C and 30 deg C), 5,4 and 5.6 water molecules per phospholipid, respectively, are unavailable for solvation.