Regular folding chain conformation of the deoxyribonucleic acid in chromatin. X-ray diffraction and selforganization.

The following model is proposed for the structure of deoxyribonucleic acid (DNA) in chromatin: The DNA in a nucleosome is folded seven times to and fro on the surface of a cylindrical protein nucleus. There exist 3.5 DNA hairpins. The seven arms of the hairpins contain twenty DNA base pairs each. The six loops of the DNA hairpins contain ten DNA base pairs each. Consistently with the experiment, the model gives X-ray small-angle diffraction reflexes at 10.5 nm, 5.5 nm, 3.6 nm. The X-ray larg-angle diagram can also be interpreted by the model. Folding crystallization is the mechanism of supramolecular selfassembly giving condensation of DNA in the chromatin.