in the cases of sv40 and polyoma , where it has been shown that the supercoiling is a combined consequence of the binding of the four nucleosomal histones , h2a , h2b , h3 and h4 , and the action of n-c enzyme , the breadth of the distributions within the form i dnas poses specific problems since the work of other laboratories indicates that the number of nucleosomes on the respective minichromosomes falls within a narrow distribution of 21 .
C0019646
h2a
C0028623
nucleosomes