the influence of nucleosome structure on the activity of 2 chromatin-associated dna endonucleases , pis 4.6 and 7.6 , from normal human and xeroderma pigmentosum , complementation group a ( xpa ) , lymphoblastoid cells was examined on dna containing either psoralen monoadducts or cross-links .
C0028623
nucleosome
C0007634
cells