The applicability of extraction by trichloroacetic acid to the preparation of very lysine rich histones from the mammary gland

Abstract

The technique of De Nooij and Westenbrink (1) for extraction of very lysine-rich histones from the calf thymus was found applicable to the rabbit mammary gland. In order to increase yields and minimize heating, the tissue was pulverized with solid C0 2 prior to blending. The concentration of the TCA 4 4 Abbreviation used: TCA, trichloroacetic acid. by which histones were extracted was not critical over at least the range 2.5 to 4.5%. The final yield was about 14 mg per 100 gm of wet tissue. Only a little contamination was detected in these preparations by amino acid analyses, electrophoresis on polyacrylamide gels, and ion exchange chromatography. A systematic study of the protein extracted by a series of TCA concentrations revealed that lower (less than 2.5%) TCA concentrations extracted, together with the very lysine-rich histones, significant amounts of contamination. Chromatographically this contamination was well resolved from four peaks of very lysine-rich histone. The absolute amounts and relative proportions of the latter four components were independent of the TCA concentration used for extraction.