[Changes in the protein composition of chromatin in the presence of supplementary total histone]

Relationships have been studied between call thymus chromatin isolated in a medium of low ionic strength (0.7 mM Na-phosphate buffer, pH 7) and total histone which was added in different amounts (up to a 40-fold excess) with respect to chromatin DNA. The maximum protein/DNA ratio in chromatin-histone complexes being formed was 3.27. It has been demonstrated for the first time that with an elevation in the amount of supplementary total histone there took place a release of natural histones of chromatin, first of HI and then of H2A and H2B. It is concluded that supplementary histone interacts with DNA, modifying its interplay and chromatin protein even though the dissociation is not fixed yet.