Residual chromatin of mouse spleen nuclei after intensive nuclease treatment. Isolation and properties

Two-step treatment of mouse spleen nuclei with staphylococcal nuclease was used to isolate residual nuclear structures lacking a considerable part of chromation. Partial disruption of the nuclear envelope after the first step of digestion was shown to be essential for obtaining residual nuclear structures. Isolated residual nuclear structures contained condensed chromatin (residual chromatin) which was not solubilized upon additional staphylococcal nuclease treatment and amounted to approximately 20% of total nuclear chromatin. Residual chromatin was almost deprived of nonhistone chromosomal proteins. It contained a full complement of histones and consisted of nucleosomal chains having different lengths--from one to 50-60 nucleosomes. Some of the condensed chromatin chains were anchored to the nuclear matrix.