Lipids in Membranes - Membrane Biophysics, Biological and Medical Physics, Biomedical Engineering - page 45

400 15

300

10

200

5

100

0

0

20 30 40 50 60 70 40 50 60 70

T / ° C

° C

T /

Fig. 3.9 DSC heating thermograms of DEPE bilayers with both 1.36mole% GS and different
mole% Alm in the aqueous phase ( top to bottom 1.36mole% GS 0, 0.1, 0.15, 0.2, 0.25, 0.3, 0.5,

0.6, 0.75 or 1, respectively mole%Alm in DEPE) [ 1 ]. The left panel shows the heating thermograms
for a 20-75 ◦ C temperature range while the right panel shows a shorter temperature range mainly
showing the L α / H II phase transition

+

but experiences no further broadening. Importantly, at a higher GS/(LA) 12 level, the
L α

/ H II transition reveals the trend of independent GS/(LA) 12 -induced effects with
only a modest visibility of 0.5% Alm's effects. In a reverse investigation, different
Alm concentrations in the presence of fixed GS (1.36%) or (LA) 12 (0.2%) produce
no qualitatively different changes in T m , H and co-operativity, compared to those

due to Alm alone.
The effect of binary AMPs on T H shows remarkable features. At a low GS level
(GS-Alm ratio between 0 and 0.136) with 0.5% Alm, T H drops sharply to a much
lower value than the value for low GS alone, and slightly lower than the dropped
values of T H for high Alm ( 0.6mole%) alone. The sharp drop also occurs at a half-

GS level (GS-lipid ratio at 0.068%) compared to that (GS-lipid ratio at 0.136%)
without Alm. With an increasing GS (GS-Alm ratio between 0.136 and 0.68), T H
increases quickly to as high as the T H induced byGS alone, and continues tomodestly
increase when further increasing GS (GS-Alm ratio over 0.68) keeping T H always a
little lower than what it would be without 0.5%Alm. At a low (LA) 12 level [(LA) 12 -
Alm ratio over 0.1] with 0.5% Alm, T H sharply drops to much lower values than

∼