Reassociation of Rat Hepatoma Chromatin Protein Components with DNA

Abstract

Rat ascites hepatoma chromatin was dissociated in 2 M NaCl-5 M urea-50 mM sodium acetate (pH 6.0) and reconstituted by gradient dialysis against decreasing concentrations of NaCl in the presence of urea. The mode of reassociation of chromatin protein components with DNA was examined mainly by gel electrophoresis. Histone 1 bound to DNA during dialysis against 5 M urea containing decreasing concentrations of NaCl from 0.4 to 0.2 M, and other histone fractions bound to DNA in dialysis at NaCl concentrations from 0.3 to 0.1 M. Binding of histones to DNA was almost completed in 0.1 M NaCl-5 M urea, but about one-half of the died with DNA at this step. Some electrophoretically separated CNH proteins reassociated with DNA at almost the same time that histones bound to DNA, and other proteins reassociated with DNA after completion of binding of histones to DNA.