A rapid and gentle method for the salt extraction of chromatin core histones H2A, H2B, H3 and H4 from rat liver nuclei.

A complex of histones H2A, H2B, H3 and H4 has been isolated from purified rat liver nuclei by a method which is both gentle and rapid. Nuclei were homogenised in 0·25 Μ sucrose and the residual nuclear material obtained after centrifligation was adsorbed on calcium phosphate gel. After removing histone H1 from the adsorbed material by washing with 1M NaCl in 25 mM sodium phos phate buffer, pH 6·0, histones H2A, H2B, H3 and H4 were eluted together, with 2 Μ NaCl in 25 mM sodium phosphate buffer, pH 7 · 0. The core histones so obtained migrated as a single sharp band on polyacrylamide gel electrophoresis under non denaturing conditions. Fractionation of the freshly prepared core histones on a Sephadex G 100 column yielded two major protein peaks. The peak having the larger elution volume contained histones H2A and H2B in equal amounts while the peak with the smaller elution volume contained all the four histones. Histones H3 and H4 were present in larger proportions in the second peak.