Structural Investigations on Isolated Chromatin of Higher‐Order Organisation

Abstract
Rat liver chromatin of a high structural order was prepared by a method avoiding drastic mechanical stress, as well as strong changes of the ionic strength, and was investigated by small-angle X-ray scattering. The quaternary structure of completely hydrated chromatin in solution is apparently a solenoid with a diameter of about 32-34 nm. Gel chromatography of this chromatin yields solutions containing mainly quaternary structures with differing portions of tertiary structure. Decrease of the ionic strength results in an increase of loosening and unfolding of quaternary structures. Reconstitution by readjustment of the physiological ionic strength indicates slight differences between reconstituted and original higher-order structures.