The selective extraction of histones from rye chromatin.

The selective extraction of histones from rye chromatin was studied using three different methods. Extractions with NaCl-phosphate buffers at pH5.5 gave results similar to those already obtained with other types of chromatin. Histone H1 was selectively extracted with 0.6 M NaCl-0.001 M PO4, while the selectivity of dissociation of the other fractions was reduced at higher NaCl concentrations. The use of phosphate-urea buffers at pH5.5 also revealed that the histones were dissociated at the same concentrations as were calf thymus histones. Histone H1 was extracted with 0.5 M PO4-1 M urea; H1, H2A, and H2B were extracted with 0.8 M PO4-2 M urea; and all histones were removed with 0.8 M PO4-5.3 M urea. It was, however, observed that the dissociated rye histones H2A and H2B were unstable in these buffers. This instability was maximum in the presence of 3 M urea, where both histones were absent from the extracted proteins and the residual nucleoproteins. Finally, a solution of 30% ethanol-0.35 M NaCl-6 M urea produced a rye nucleoprotein fraction containing only histone H1.