Organization of internucleosomal DNA in rat liver chromatin

A detailed analysis of the length distribution of DNA in nucleosome dimers trimmed with exonuclease III and S1 nuclease suggests that the previously described variation of internucleosomal distance in rat liver occurs, at least for a subset of the nucleosomes, by integral multiples of the helical repeat of the DNA. Results obtained upon digestion of chromatin with DNase II further suggest that lengths of internucleosomal DNA are integral multiples of the helical repeat of the DNA plus approximately 5 bp. Restraints imposed by these features on the arrangement of nucleosomes along the fiber are discussed.