following micrococcal nuclease digestion , nuclei were sedimented to obtain a chromatin fraction released during digestion ( s1 ) and then lysed in tris ( hydroxymethyl ) aminomethane- ( ethylenedinitrilo ) tetraacetic acid- [ ethylenebis ( oxyethylenenitrilo ) ] tetraacetic acid and centrifuged again to yield a second solubilized chromatin fraction ( s2 ) and a pelleted fraction ( p2 ) .
C0007610
nuclei
C0008546
chromatin