[Effect of acid extraction of basic proteins on the binding of acridine orange by cell chromatin]

The binding of acridine orange to chromatin of fixed human lymphocytes is increased after stepwise removal of histones by hydrochloric acid. No changes in the dye-binding features of the cells were found after f1 histone extraction (0.01 N HC1). Additional extraction of f2 and f3 by 0.05 N HC1 (partial extraction) and by 0.25 N HC1 (more complete extraction) resulted in increased binding of acridine orange (1.9 and 2.5 of that of the control, respectively).9222