Finestructure and template activities of DNA-histone complexes reconstituted in the presence and absence of urea.

Several DNA-histone complexes were reconstituted in the presence and absence of urea. The fiber size of DNA-histone H1 complex was about 20 A in width with knobs 100 to 250 A in diameter interspersed at an average interval of about 1,100 A. H1-was associated with DNA segments corresponding to a DNA size of fewer than 100 base pairs. DNA-histones H2A, H2B, H3 and H4 complex consisted of globular subunits 100 to 150 A in diameter alternating with thin strands, like beads on a string. DNA-whole histones complex was 200 to 250 A in width and had a condensed configuration. The nuclease digestion pattern of the complexes containing histones H2A, H2B, H3 and H4 was regular, similar to that of chromatin, and was disrupted by urea. The complex containing H1 was inactive for in vitro RNA synthesis by escherichia coli RNA polymerase, whereas the other complexes were active. The complexes reconstituted in the absence of urea had template activities slightly less than in the presence of urea.