phase transition temperature of phosphatidylethanolamine with same fatty acyl
chains as phosphatidylcholine is higher because of smaller polar head. DPPC and
DPPE have same fatty acyl chains of palmitic acid but phase transition temperatures
of DPPC and DPPE are41
C and 63
C, respectively. Introduction of cis double
bond expands distance between phosphatidylcholine molecules because of its kink
Fig. 4.5 Phase transition of DPPC multi-lamellar liposomes observed by freeze-fractured electron
microscope
Multi-lamellar liposomes were prepared and freeze-fractured from different temperatures. The
replicas were observed by scanning electron microscope (SEM)
30
35
40
45
50
55
0.98
1.00
1.02
1.04
1.06
1.08
1.10
Temperature[°C]
Density [g/cm
3 ]
Fig. 4.6 Density change in
DPPC multi-lamellar
liposomes
Multi-lamellar liposomes of
dipalmitoyl
phosphatidylcholine
(DPPC)were prepared and
density was measured at
various temperatures
4.2 Phase Transition of Lipid Bilayer Membranes
63