| Research Abstract |
1. Under high pressure the sub transition, which is composed of two reversible phenomena, i.e., the 4th and 3rd transitions, is obtained from the sample which is conditioned by the high pressure melting. The motion of head group, i.e., choline, phosphoric acid, glycerine, and acyl parts of priospholipids, is monitored at the 4th and 3rd transition by Raman scattering methods, which is verified head groups closely take part in the sub transition.
2. Dehydration of head group, i.e., changes from water or super cooled water' to ice', promotes movements of head group and those of hydrocarbon chain connected with it. it is also verifies that conditions, which is surrounded by two parallel plates of head groups, obstruct the growth of ice, i.e., the state of super cooled water continues down to extremely low temperature (e.g., -45 C in the case of DSPC contained 15 wt% water).
3. In cooling process super cooled water in the excess water and the water layer between phospholipids bilayer in multilamellar freezes at -2OﾟC and 45ﾟC , respectively, where the excess water means the extra water besides water layer in multilamellar. Each case shows homogeneous or heterogeneous ice conformation with hexagonal symmetry in the excess water or the water layer, respectively.
4. The sub transition appears without special condition, e.g., the long-term cooling process under A2. as like keeping phospholipids around 4ﾟC for more than 72 hours, using some kinds of phospholipids having C_n=2O, 22 and 24/chain. In these cases two phenomena, which closely corresponds to the 4th and 3rd transitions under high pressure, compose the sub transition and occur reversibly.
|
