抄録
We found two doublet signals A and B in 2D-NMR of dipalmitoyl-phosphatidylcholine–D2O system at a low water content below the temperature of the onset of the main phase transition, i.e. in the β′-crystalline (Lβ′) phase. The splitting of each doublet becomes minimum at the onset of the transition. The signal A decreases in intensity with a slight increase of its splitting as the temperature increases further, accompanying the marked growth of the signal B in its intensity and splitting. These features of two doublets in the Lβ′ phase and at higher temperatures have never been noticed. The signals A and B were ascribed to the tightly bound water and the loosely bound water, respectively. These assignments were confirmed by the theoretical calculations of the splitting of the doublet A for all possible number of the tightly bound water molecules.
