In order to approach and clarify the effect of poly(ADP-ribose) on the nucleosomal structure, polynucleosomes from calf thymus were incubated with long poly(ADP-ribose) chains prepared in vitro and examined by ELISA with antibodies directed against the five individual histones H1, H2A, H2B, H3 and H4 as well as against two synthetic peptides in residues 1-25 of H2B and 130-135 of H3 VSports手机版. The results showed that: (i) free ADP-ribose polymers did indeed interact with the nucleosomes; (ii) the accessibility of epitopes recognized by any of the different antibodies was altered, the binding of antibodies being increased or decreased depending on the quantity of poly(ADP-ribose) added thereby suggesting a modulation in nucleosome structure; (iii) for any ADP-ribose polymer concentration, core histones as well as histone H1 were always recognized by their respective antibodies, thus suggesting that poly(ADP-ribose) does not seem to cause complete stripping of histones from nucleosomal DNA. .