Purification of DNA by anion-exchange chromatography

Column chromatography has evolved to provide a rapid and effective alternative to more laborious methods for preparing high-quality DNA, such as CsCl-gradient centrifugation. This unit describes the use of a column made of a unique anion-exchange resin that selectively binds nucleic acids, allowing rapid separation of DNA from contaminating RNA, proteins, carbohydrates, and metabolites. The procedure employs columns supplied by QIAGEN; other preparation methods are available from other suppliers. A crude nucleic acid sample (usually a cleared cell lysate) is applied to the QIAGEN tip under conditions that favor binding. Contaminants in the sample are washed from the column with a moderate-salt buffer, and DNA is eluted using a high-salt buffer.