Binding of N-hydroxy acetylaminofluorene to eu- and heterochromatin fractions of rat liver in vivo.

The in vivo binding of N-hydroxy acetylaminofluorene (N-OH AAF) to rat liver DNA was studied in hetero- and euchromatin fractions prepared by sedimentation through sucrose gradients. The greater transcriptional capacity of the slowly sedimenting (euchromatin) fractions was confirmed by their enhanced incorporation of radioactive precursors into RNA in vivo and their increased template activity for in vitro RNA synthesis by purified RNA polymerase. N-OH AFF was bound in 4- to 5-fold greater amounts to euchromatin DNA than to heterochromatin 2 h after a single injection of the compound. However, the bound carcinogen appeared to be eliminated more rapidly from euchromatin than from heterochromatin by DNA repair processes.