Transcriptional features of fractionated human breast tumor chromatin

By means of controlled mechanical shearing it was possible to fractionate human breast tumor chromatin in "active" and "inactive" species, according to their in vitro template activity, using Escherichia coli RNA polymerase. The "active" molecules can be resolved in three well defined regions in an exponential sucrose gradient, showing approximately 300 times the efficiency for synthesizing ribonucleic acid, relative to the chromatin which migrated fastest. This technique could provide the initial tool to isolate eu-and heterochromatin from native human chromatin.