[Stability of DNA-protein complexes in cell nuclei of the rat liver during aging].

Elevation in tightness of bonds between newly synthesized DNA and nuclear matrix proteins was increased in rat liver cells in ageing as shown by means of nucleoproteidecelite chromatography. With ageing content of loosely bound non-histone proteins was decreased in chromatin, tightly bound proteins were increased, while residual proteins remained unchanged. At the same time, elevated level of lamin B and alterations in content of some other polypeptides were found in the fraction of residual proteins of chromatin in aged animals. The phenomenon observed i.e. elevation of tightly bound DNA-protein complexes, enabled to suggest that alterations in composition of chromatin residual proteins were responsible for an increase in the rate of association in DNP complexes in ageing but not the accumulation of cross-links in the complex structure components.