THE FRACTIONATION OF THE HISTONES OF CALF THYMUS AND CHICKEN ERYTHROCYTES BY CATION-EXCHANGE CHROMATOGRAPHY WITH SODIUM SALTS

The histone extracted from the nucleoprotein of calf thymus and chicken erythrocyte nuclei at pH 1.8 was more stable than that extracted at less than pH 1.5. Extraction directly from isolated nuclei avoided the deleterious effects of dialysis and of neutral pH. Fractionation by cation-exchange chromatography on the sodium form of Amberlite IRC-50, with "stepwise elution" by various sodium salts, recovered more than 90% of the chicken erythrocyte histone in at least seven components. About 75% of the calf thymus histone was eluted in four peaks; one of these was shown to be identical with the lysine-rich component, while the other three coincided with the arginine-rich peak eluted by barium acetate from barium IRC-50. These preparations of histone chloride were not degraded in sodium salt solutions, but tended to aggregate, especially in the presence of barium ion.