Activation of chromatin by acetylation of histone side chains.

The ability of calf thymus chromatin to support DNA-dependent RNA synthesis is markedly increased by modification of the histones with acetic anhydride. The extent of chemical acetylation of histones H2a, H2b, H3, and H4 required for the increase of template activity of the chromatin is within that which can be achieved enzymatically in the cell. The evidence suggests that the acetylation of histone side chains stimulates the rate of chain elongation during transcription of chromatin.