Antigenicity of histones in various chromatins.

Antisera specific to purified histone fractions are used to assess the antigenicity of the histones present in chromatin derived from various sources. The results indicate that the antigenicity of the histones present in chromatin is markedly diminished as compared to the antigenicity of the histones free in solution. The antigenicity of histones in chromatins derived from three different tissues of the rat is very similar. The antigenicity of the histones present in chromatin derived from calf thymus is higher than that of the histones present in rat thymus. It is concluded that the major reason for diminished antigenicity of histones in chromatin is that the histones are complexed in the nucleosome conformation and that the antigenic determinants residing in histones in various chromatins are exposed to similar degrees.