Figure 3.
CTII and CTI induce non-bilayer structures containing PC in PC+CL liposomes, but not in PC liposomes lacking CL. 1H-NMR spectra derived from the N+(CH3)3 groups of PC in sonicated unilamellar liposomes composed of PC treated with CTII (A), PC+ 5mol% CL treated with CTI (B) and PC+ 5mol% CL treated with CTII (C) at a total lipid concentration 1.4 × 10−2 M in the presence of K3[Fe(CN)6] (10 μL of saturated K3Fe(CN)6 solution per 1 mL of liposomes) and 1.75 × 10−4 M CTII or CTI at 18 °C. All liposome samples were incubated for 30 min at 18 °C in a tube for 1H-NMR prior to adding K3[Fe(CN)6] and then incubated for another 15 min prior to adding CTII or CTI. The amount of non-bilayer immobilized PC was estimated by calculating the computer-extrapolated area under the high-field peak on the shoulder of N+(CH3)3 of the 1H-NMR signal from PC molecules on the outer leaflet of liposomes (see arrow). Each 1H-NMR spectrum shows representative 1H NMR traces from three independent experiments that showed similar results. Each sample was measured in triplicate.