Isolation of nonhistone chromosomal protein from calf thymus

Abstract 1. 1. A method for the preparation of nonhistone chromosomal proteins from calf thymus under mild conditions was proposed. 2. 2. Calf thymus chromatin was dissolved in 0.1 M Tris HCl (pH 7.9) containing 2 M NaCl and 5 M urea to dissociate it into the chromosomal proteins and DNA. Then, the DNA was precipitated selectively by adding LaCl 3 at a concentration of 0.0135 M, leaving the proteins in the supernatant. The nonhistone chromosomal proteins in the supernatant were separated from histone by CM-cellulose column chromatography with 0.01 M Tris-HCl (pH 7.9) containing 5 M urea. 3. 3. The amino acid composition of the protein was analyzed.