Quaternary structure of chromatin.
Neutron scattering experiments on chromatin solutions have been carried out at Bragg spacings several times larger than in any previous x-ray work. A new series of very low angle reflections at about 400, 200, and 140 A were observed. These reflections demonstrate the existence of a higher order structure of the 100 A unit fibril. A coiled-coil model with a major pitch of 500 A and a radius of center to fibril center of 130 A is proposed to explain the results.
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