Isolation of the yeast histone octamer.

Procedures for the extraction and purification of the yeast histone octamer are described. Either mechanical disruption, yielding chromatin fragments, or spheroplast formation with subsequent nuclear isolation was employed. A hexahistidine tag was inserted in the N-terminal region of histone H2B, permitting resolution of the histone octamer from high-salt extracts of nuclei or chromatin to near homogeneity. The histone octamer purified in this way was fully active in reconstitution of nucleosomes.