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Journal of Chemical Physics, Vol.115, No.1, 601-607, 2001
Nonfreezing water confined in water layer of multilamellar L-alpha, distearoyl phosphatidylcholine in temperature range between 0 degrees C and-190 degrees C
Where multilamellar phospholipid water exists, e.g., inside or outside of the multilamellar phospholipid, depends largely on the percentage of water content. For example, the multilamellar L-alpha, distearoyl phosphatidylcholine (DSPC) with 44 wt % water content carries water in excess water regions as well as in the water layer inside of the multilamellar DSPC. This excess water freezes at about -20 degreesC in forms ranging from super-cooled water to homogeneous ice with a hexagonal symmetry. On the other hand, when no excess water exists, e.g., in cases of multilamellar DSPC containing 15 wt % or 11 wt % water, water is contained entirely in the water layer inside of the multilamellar DSPC. When multilamellar DSPC contains 15 wt % water, the state of super-cooled water in the water layer is maintained at about -45 degreesC and then changes into heterogeneous ice or into many ice nuclei with a hexagonal symmetry in the temperature region of less than -45 degreesC. In the case of multilamellar DSPC with 11 wt % water content, however, the state of super-cooled water in the water layer remains unchanged even down to -190 degreesC. X-ray diffraction results prove that the super-cooled water in the water layer of multilamellar DSPC containing 11 wt % water does not freeze even down to -190 degreesC.