Stable DNA-polypeptide complexes from eukaryotic nuclei purified on heparin Sepharose

A novel simple method using affinity chromatography on Heparin Sepharose CL-6B is described for purification of stable DNA-polypeptide complexes from preparations of eukaryotic nuclear DNA. These complexes resist RNase A and proteinase K treatment and copurify with DNA on phenol extraction. The content of heparin-binding complexes amounted to about 20% of the total DNA quantity and 60 to 80% of nitrocellulose-retained DNA, being similar in preparations of DNA from calf thymus, chicken erythrocytes and cauliflower inflorescence. This content was influenced by the size of DNA fragments and the presence of dithiothreitol. The heparin-binding fraction was shown to represent a definite type of complexes which is different from the other(s) retained on nitrocellulose.