Fractionation of non-histone chromatin proteins from pig liver and kidney by means of immobilized histone H3.

The non-histone chromatin proteins (NHCp) from pig liver and kidney have been partially fractionated in non-denaturing conditions by the use of histone H3 immobilized on agarose and the fractions obtained have been analysed by SDS-polyacrylamide gel electrophoresis and amino acid analysis. At least six different fractions have been obtained by successive increases of the ionic strength of the medium. Few NHCp have been evidentiated with subunit molecular weights 55,000 and less than 30,000, which diaplay a remarkably high affinity for histone H3, and require 5 M urea to be displaced from the immobilized histone. The elution patterns of the NHCp from liver and kidney, although very similar, reveal some significant differences between the two tissues, which are undetectable by SDS-electrophoresis and which are most likely due to tissue specific proteins. This histone-affinity chromatography appears to be a promising approach for the analysis of specific histone-NHCp interactions, and as a first step for NHCp purification.