Hyde J E, Walker I O
Nucleic Acids Res. 1975 Mar;2(3):405-21. doi: 10.1093/nar/2.3.405.
Symmetry considerations of the kind of structures which can be generated when dimers of histones f2al-f3 and f2a2-f2b interact lead to the following conclusions: chromatin subunits based on closed-shell structures give rise to discrete, non-interacting nucleoprotein subunits with the histones arranged at random along the DNA chain; open structures based on infinite helices give rise to highly ordered, regular arrangements of dimers. A model is proposed in which helical polymers of f2al-f3 and f2b-f2a2 form a central core with the DNA helically arranged around it. The helical repeat contains 9.6 turns of B-form DNA and one molecule each of f2al, f2a2, f2b, f3 and f1. The pitch of the helix is 53Angstrom and the other diameter 130Angstrom. The protein molecular repeat is 106Angstrom.
当组蛋白f2al - f3和f2a2 - f2b的二聚体相互作用时可能产生的这类结构的对称性考量得出以下结论:基于闭壳结构的染色质亚基会产生离散的、非相互作用的核蛋白亚基,其中组蛋白沿DNA链随机排列;基于无限螺旋的开放结构会产生高度有序的二聚体规则排列。提出了一个模型,其中f2al - f3和f2b - f2a2的螺旋聚合物形成一个中心核心,DNA围绕其呈螺旋状排列。螺旋重复包含9.6圈B型DNA以及f2al、f2a2、f2b、f3和f1各一个分子。螺旋的螺距为53埃,外径为130埃。蛋白质分子重复为106埃。