Preparations of Histone and Nucleosome

In eukaryote cells chromatin is composed of DNA, histone and nonhistone proteins. Among them histone was isolated from chromatin by the replacement with protamine. followed by a gel filtration for the separation of whole histone from the residual protamine. Whole histone was further fractionated to two fractions, A and B. These histone preparations were more native and soluble than that obtained by acid extraction. A DNA-protein complex, nucleosome was prepared by the DNase II digestion of calf thymus chromatin, but perfect digestion to nucleosome monomer could not be carried out. Protein: DNA ratio of this nucleosome (2.07) suggested that nonhistone proteins were also present in nucleosome