FIG. 3.

Agarose gel electrophoresis. (A) DNA retardation assay. The plasmid pIL-12 (1 μg) and several amounts of peptide [K]₁₈S₁₂ were mixed in 20 μl of HBS, followed by electrophoresis on a 0.8% agarose gel stained with ethidium bromide. The charge ratios (peptide/DNA) are indicated above. Marker represents the DNA size marker (λDNA/HindIII+EcoRI; Sangon). (B) DNase I protection assay. The plasmid pIL-12 was preincubated with the peptide [K]₁₈S₁₂ at the charge ratio indicated above, followed by treatment with DNase I as described in Materials and Methods. The integrity of the DNA was compared with that of native DNA.