Study of heterogeneity of chromatin endonuclease fragments, using fractionation by step-wise endonucleolysis
Kharchenko, E.P.; Nalivaeva, N.N.; Kolesnikova, E.I.; Fedotova, E.A.
Biokhimiia 44(10): 1768-1775
1979
ISSN/ISBN: 0320-9725 PMID: 508854 Document Number: 147542
Isolated nuclei from rat liver were incubated at different time intervals under conditions, optimal for manifestation of the Ca, Mg-dependent endonuclease activity. After each of the 6 endonucleolyses chromatin was extracted and 6 chromatin fractions (I--VI) and "residual" chromatin were collected. A comparative analysis of the "early" (I--III) and "late" chromatin fractions revealed an increased RNA content in the "late" fractions and changes in the composition of the non-histone proteins. Electrophoresis in acrylamide gel concentration gradient demonstrated that fractions I--III predominantly contain high molecular weight fragments whereas fractions IV-VI are represented by highly fragmented chromatin. Each fraction was characterized by peculiar shapes of alkaline denaturation curves and by heterogeneity of charges of their constituent chromatin fragments.