期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1978
卷号：75
期号：1
页码：103-107
DOI：10.1073/pnas.75.1.103
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The idea that DNA in chromatin can be packed smoothly, without breaking of base-stacking interactions, has been explored by both energetical estimations and stereochemical model building. A model of deformed DNA is built that fits reasonably to the known dimensions of a nucleosome. The model has slightly changed torsion angles in the sugarphosphate moieties relative to B DNA, varying gradually along the chains. The angle between planes of adjacent base pairs varies between 1 and 7 degrees. This model of deformed DNA does not have any unusually close nonbonded contacts and is evidently not the only possible model of smooth packing of DNA in chromatin. An energetical estimation of the critical radius of curvature of a smoothly bent DNA molecule is made using approximate potential functions for different van der Waals contracts in the B DNA structure. The critical radius of curvature of the deformed DNA-axis is close to the radius of a nucleosome (similar to 50 A). The smooth packing is a good alternative to models of kinked folding of DNA in nucleosomes.
