Structure of chromatin subunits: an endonuclease Serratia marcescens study

Abstract
Electrophoretic properties of chromatin subunits – nucleosomes – obtained by treatment of chromatin with the Serratia marcescens endonuclease have been studied. Double-stranded breaks of DNA between adjacent nucleosomes do not necessarily lead to their disjunction. Fragmentation of the DNA within the nucleosomes may proceed simultaneously with the breakdown of the DNA between the nucleosomes at early stages of the endonuclease digestion. Electrophoretic mobility and chromatographic properties of mononucleosomes, their dimers and trimers with internally degraded DNA was not changed. It has been deduced that the integrity of chromatin particles with internally fragmented DNA is supported by histone interaction inside and between the nucleosomes.