X-ray scattering studies. (A) Small-angle x-ray scattering scans of RPR120535/DNA complexes at various cationic lipid-to-DNA ratios. Symbols ○, □, and • correspond to RPR120535/DNA complexes from zones A (RPR120535/DNA charge ratio: 0.33), B (charge ratio: 1.65), and C (charge ratio: 6), respectively. (B) Because complex samples were prepared at 0.5 mg DNA/ml and concentrated 10-fold by ultracentrifugation, small-angle x-ray scattering scans were performed at 5 mg/ml on both DNA alone (○) and RPR120535 aqueous solution (□).