Fractionation of histones from calf thymus and posterior silkglands by countercurrent distribution.

Abstract

1. A countercurrent distribution method was applied to the fractionation and purification of histones. By the distribution with water and butanol-2 solvent systems containing various concentrations of urea and trichloroacetic acid, slightly lysine-rich histones from calf thymus and posterior silkglands were further fractionated into seven and six components, respectively, and an arginine-rich histone from calf thymus into nine components. 2. Although no significant differences were found in the distribution patterns of slightly lysine-rich histones from calf thymus and posterior silkglands, obvious differences in amino acid composition and N-terminal amino acids between these two histones were observed. 3. Of the fractions obtained by the distribution, AG1 and AC3 fractions from an arginine-rich histone appeared to be the most homogeneous on gel electrophoresis and N-terminal amino acid analysis. 4. Thus, the countercurrent distribution method has proved to be an excellent tool for purification of histones, and has been suggested to be applicable to other histone fractions, if we choose solvent systems of suitable distribution-coefficient values by changing the concentrations of urea and trichloroacetic acid in the solvent system of water and butanol-2.