Predominance of Core Histones in Formation of DNA-Protein Crosslinks in γ -Irradiated Chromatin

Chromatin and a subunit of chromatin containing a complex of DNA and the core histones--H2A, H2B, H3, and H4--have been prepared from cultured Chinese hamster cells. Comparison of the formation of radiation-induced DNA-protein crosslinks in whole chromatin with that in the DNA-core histone complex has demonstrated that the core histones are the specific proteins involved in crosslinking. γ irradiation of the chromatin subunit in the presence of radical scavengers has shown the hydroxyl radical to be the most effective aqueous radical intermediate for the promotion of crosslinking and the solvated electron and superoxide radical to be essentially ineffective.