Fractionation of whole histone by partition chromatography on Sephadex G-25

Whole histone from calf thymus was fractionated by partition chromatography on the basis of distribution between an aqueous phase immobilized on Sephadex G-25 beads and mobile organic phases containing various concentrations of trichloroacetic acid. The chromatography was carried out by stepwise elution with five upper phases from water and butanol-2 solvent systems containing 4 M urea and 0.1-1.5% trichloroacetic acid, and finally water. Of the six peaks obtained, two (peaks 1 and 2) contained arginine-rich histones. Although these peaks were still heterogeneous electrophoretically, the band corresponding to F2al was observed only in the electrophoretic pattern of peak 1 and the main fraction in peak 2 was F3. A histone fraction having nearly equimolar amounts of arginine and lysine was obtained from peak 3. Its amino acid composition was similar to that of F2a2. Slightly lysine-rich histone obtained from peak 4 showed an amino acid composition typical of F2b. Peak 5 contained a histone fraction with a ratio of lysine/arginine of 6.14, showing a single band on gel-electrophoresis. Very lysine-rich histone (F1) was obtained from peak 6, and the electrophoretic pattern of this fraction showed a single band.