EN
A fast two step method of agarose gel electrophoresis for separation of different conformational forms of DNA is described. In the first step the gel is run in the buffer without ethidium bromide and then the gel is stained with that dye. After staining the second step of electrophoresis is performed in the buffer without ethidium bromide. This two step procedure allows one to receive very good resolution between bands corresponding to relaxed, supercoiled, open circular, and linear forms of DNA.