Fig. 1.

Changes in circular dichroism spectra induced by cationic liposomes. Plasmid DNA pGEMT-VP7 was mixed with increasing concentrations of liposomes. The DNA/liposome systems obtained were lyophilized and then rehydrated in 10 mM Tris–HCl, pH 7.4, containing 154 mM NaF. CD spectra were recorded in a JASCO J-810 spectropolarimeter using a quartz cuvette with a 0.5-cm optic path. During the assay, the temperature was kept at 20°C. a CD spectroscopy between 220 and 320 nm was performed for 0.010 mg DNA mixed with 0 (black line), 0.2 (gray line), and 1.0 mM (light gray line) cationic lipids (0.4, 0.6, and 0.8 mM lipid concentrations were excluded from the graph in order to clarify observations) and b changes in the 275-nm band as a function of lipid concentration. Data were expressed as mean of five experiments ± SD, and differences between groups were tested using the hypothesis test. Data denoted with an asterisk were significantly different with respect to DNA without liposomes (p < 0.05)