Studies on histone oligomers. III. Effects of salt concentration and pH on the stability of histone octamer in chicken erythrocyte chromatin.

The core proteins dissociated from chicken erythrocyte chromatin in high salt and at various pHs were characterized according to their histone composition and the oligomeric degree of histones. The dissociation profile of histones from chromatin by salt was also examined. The type of histone oligomers formed depended on pH during dissociation and fractionation. Heterotype histone oligomers were obtained at pH 6--9, while the octamer dissociated into homotype histone oligomers at pH 4--5. At pH 8, the octamer was in an equilibrium with the (H2A . H2B)(H3 . H4)2 hexamer, the (H3 . H4)2 tetramer, and the (H2A . H2B) dimer. At pH 5, the octamer dissociated into homotype dimers, presumably (H2A . H2B) and (H3 . H4).