Different pRSVcat DNA preparations using the methods indicated were introduced into the indicated cell lines by liposome-mediated transfection, and the efficiencies determined by measuring CAT expression levels after 40 h. Each bar represents the mean of 4 independent transfections (2 transfections with each of 2 independent plasmid preparations). The highest transfection efficiency was achieved with QIAGEN Plasmid Kits.
Neutralized bacterial lysates are cleared by centrifugation. The cleared lysate is then loaded onto the anion-exchange tip where plasmid DNA selectively binds under appropriate low-salt and pH conditions. RNA, proteins, metabolites, and other low-molecular-weight impurities are removed by a medium-salt wash, and ultrapure plasmid DNA is eluted in high-salt buffer. The DNA is concentrated and desalted by isopropanol precipitation and collected by centrifugation.