Fractionation of chromatin fragments on columns of Biogel A50-m at different salt concentrations

Abstract

Nuclease fragmented chromatin was chromatographed on Biogel at various NaCl concentrations. The yield of eluted chromatin, and its H1/core histone ratio was minimal at 0.18 M NaCl where the ratio of H1 subtypes H1c/H1ab was maximal. Therefore, the eluted material was aggregation-resistant chromatin while aggregatable chromatin remained on the columns. Previous results were interpreted as H1 depletion of chromatin by ion-exchange properties of Biogel, but the primary phenomenon is now seen as a separation of classes of chromatin that differ in sensitivity to salt-induced aggregation. At very low salt concentrations, Biogel chromatography can be used without concern for H1 depletion.