[Changes in the compactness of nucleosome chromatin from the bovine liver during aging]

Electrophoresis methods used to study the fragments of chromatin revealed under the effect of Ca,Mg-dependent endonuclease on it have permitted establishing that stability of chromatin to the nucleosome level increases with aging. Changes in the compactness of the chromatin structure with aging make the accessibility of the linker DNA to nuclease lower the size of DNA fragments corresponding to mononucleosomes increasing from 192 +/- 5 pairs of bases to 209 +/- 5 pairs. Stabilization of the chromatin structure begins from certain nucleosomes which become more compact with the age. When analyzing basic proteins of chromatin by electrophoresis in different systems no qualitative changes were found in the subfraction composition of histones with aging, that permits supposing nonhistone proteins of chromatin and histone H1 to participate in the change of the chromatin structure compactness with the age.