Fractionation of eukaryotic DNA by pulsed field gel electrophoresis. Enzymatic nature of the formation

The data presented here confirm the possibility of enzymatic formation of discrete DNA-fragments, appearing during the fractionation of lysed nuclei by FIGE. Teniposide-dependent pattern of DNA-fragments and occurrence of protein-linked DNA breaks suggest that discrete cleavage of intact nuclear DNA is modulated by DNA-topoisomerase II. It is pointed that pulsed field gel electrophoresis may be a useful method to study higer-order chromatin structure.