Published in: J. Molec. Biol. vol. 68, no. 1, pp. 115-124 (July, 1972):

"A Super-coil Model for Nucleohistone".

J. F. Pardon and M.H.F. Wilkins

Medical Research Council Biophysics Unit, King's College,
Department of Biophysics
26-29 Drury Lane
London, W.C.2, England


Abstract:

X-ray diffraction from fibre and gel specimens of nucleohistone include low-angle diffraction that is not given by DNA or histone alone. The observed maxima do not alter in position with change in nucleohistone concentration although the intensity distribution varies.

A model is proposed for the nucleohistone complex in which the DNA double-helix is constrained to form a super-helix with pitch 120 Angstroms and radius 50 Angstroms. Changes in diffraction for different concentrations of nucleohistone are explained by packing together the super-helical molecules. A general theory for packing and precise groupings of helices is considered. The relation between the super-coil and structures observed in the electron microscope is discussed.


Additional References:

1. PubMed Listing of Articles Related to this Article:

2. "Ultrastructural Continuity between Active and Repressed Chromatin".


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