Chromatin v Bodies: Isolation, Subfractionation and the Physical Characterization

Abstract

Monomer chromatin subunit particles (υ1) have been isolated in gram quantities by large-scale zonal ultracentrifugation of micrococcal nuclease digests of chicken erythrocyte nuclei, υ1 can be stored, apparently indefinitely, frozen in 0.2 mM EDTA (pH 7.0) at ≤-25°C. Aliquots of the stored monomers have been subfractionated by dialysis against 0.1 M KCI buffers into a soluble fraction containing equimolar amounts of H4, H3, H2A, H2B associated with a DNA fragment of ∼130-140 nucleotide pairs, and a precipitated fraction containing all of the histones including H5 and HI associated with DNA fragments. The total υ1 and the KCI-soluble fraction of υ1 have been examined by sedimentation, diffusion, sedimentation equilibrium ultracentrifugation, low-angle X-ray diffraction, and electron microscopy. Physical parameters from all of these techniques are presented and correlated in this study. © 1976 Information Retrieval Limited.