Reconstitution of chromatin core particles

Abstract
Chromatin core particles [chicken blood cell nuclei] containing 140 base pairs (bp) of DNA plus the inner histones, can be nearly quantitatively formed either by reassociation from 2 M NaCl or by reconstitution from salt extracted histones and DNA. The reassociated or reconstituted particles appear to be identical with the native particles in all physical properties examined (sedimentation velocity, histone content, circular dichroism, and melting) as well as in their patterns of digestion by micrococcal nuclease, DNase I and trypsin. In the presence of excess DNA, no half-particles are formed. In the presence of excess histone, aggregated structures are formed in addition to 11S core particles.