Studies on Adrenal Histones: CHARACTERIZATION, BIOSYNTHESIS, ENZYMATIC PHOSPHORYLATION, AND ACETYLATION OF HISTONES FROM A HUMAN ADRENAL CARCINOMA

Abstract

Abstract Histones F1, F2a, F2b, and F3 were isolated from a human adrenal carcinoma. The fractions were purified by chromatography on carboxymethyl Sephadex and characterized by amino acid analysis and disc electrophoresis. The histones were comparable to calf thymus histones in amino acid composition and electrophoretic patterns. Adrenal carcinoma F3 showed a more complex electrophoretic pattern than calf thymus F3. To study biosynthesis, phosphorylation, and acetylation of histones, adrenal slices were incubated with lysine-3H, Na332PO4, and sodium acetate-14C at intervals between 5 and 120 min. The rate of histone biosynthesis as measured by lysine-3H incorporation was similar for the F1 and F2b fractions and did not increase further after 30-min incubation time. The arginine-rich histone F3 showed the highest rate of lysine-3H uptake, and its biosynthetic rate was about 16 times higher than the rate of F1 biosynthesis. The incorporation of Na332PO4 and sodium acetate-14C increased with time in all histone fractions. The rate of phosphorylation and acetylation as indicated by the specific activities of the histones was similar in the F1, F2a, and F2b fractions. The F3 histone showed the highest rate of 32P and 14C uptake. However, comparison of the acetylation and phosphorylation of the histones in relation to their biosynthetic rate suggests that the turnover of histone-bound phosphate-32P and acetate-14C is faster in the lysine-rich fractions F1 and F2b than in the arginine-rich histones.