| Abstract: | The concentration of free phosphate groups is measured in rat liver chromatin after DNase II digestion using polylysine titration. The unsheared chromatin completely precipitates at lysine/DNA phosphate ratios of 0.5 to 0.6. Digestion of the chromatin reduces the lysine/DNA phosphate ratio of complete precipitation by about 0.2 units suggesting the removal of free phosphate groups. The two chromatin fractions: MgC12 insoluble (template-inactive) and Mg12 soluble (template-active) chromatins precipitate at about the same lysine/DNA phosphate ratio. Some 15% of the MgC12 soluble chromatin remains in solution at any polylysine concentration. The removal of histone H 1 FROM THE MgC12 insoluble chromatin increases the lysine/DNA phosphate ratio by about 0.2 units suggesting that 20% of the DNA phosphate groups in nucleosomes are masked by histone H 1. |
