Selective isolation of domains of chromatin proximal to both carcinogen-induced DNA damage and poly-adenosine diphosphate-ribosylation.

Poly-adenosine diphosphate (ADP)-ribosylation of nuclear proteins has been demonstrated previously to be activated in vivo by the presence of DNA single-strand breaks and has thus been implicated to play an important role in altering chromatin structure during cellular recovery from DNA damage. Based upon these considerations, a novel immunofractionation method, using antipoly(ADP-ribose) coupled to Sepharose, has been used to enrich for those limited domains of chromatin undergoing poly-ADP-ribosylation. We have used three independent methods to verify the presence of significant levels of single-strand DNA breaks adjacent to polynucleosomes engaged in ADP-ribosylation.