THE INTRINSIC CURVATURE OF DNA IN SOLUTION
THE INTRINSIC CURVATURE OF DNA IN SOLUTION
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DOI：
10.1016/0022-2836(88)90444-5
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发表时间：
1988-05-05
影响因子：
5.6
通讯作者：
MCCALL, MJ
中科院分区：
文献类型：
--
作者：
CALLADINE, CR;DREW, HR;MCCALL, MJ
我们提出了一个详细的定量方案来解释重复序列 DNA 聚丙烯酰胺凝胶中的异常电泳迁移率。我们假设这种 DNA 在这些情况下采用超螺旋结构，并且比相同长度的直 DNA 迁移得慢，因为它只能通过较大的孔。当 DNA 的长度达到超螺旋一圈时，延迟最大，但对于较短的片段，延迟较小。我们将超螺旋的曲率归因于每种二核苷酸步骤的不同滚动角度，即通过在小凹槽侧增加分离来打开角度。主要影响是由于大约 3° 的差异。 AA/TT 和其他步骤之间的滚动值，以及大约 1° 的差异。螺旋扭转角度：我们从一些有关凝胶运行的可用数据中明确推导出这些值。该方案涉及对任何给定重复序列的超螺旋参数的简单计算，并且其与所有可用数据具有良好的相关性。我们认为这些相同的基阶角参数也与结晶低聚物的 X 射线衍射观察结果一致，特别是与 Nelson 等人关于 CGCA6GCG 的最新数据一致。我们在这里关注的是不受约束的 DNA 的内在曲率，这与与蛋白质分子相关的 DNA 曲率不同。本文代表了绝对确定的首次尝试。
We propose a detailed quantitative scheme for explaining the anomalous electrophoretic mobility in polyacrylamide gels of repeating sequence DNA. We assume that such DNA adopts a superhelical configuration in these circumstances, and migrates less quickly than straight DNA of the same length because it can only pass through larger holes. The retardation is maximal when the length of the DNA reaches one superhelical turn, but is less for shorter pieces. We attribute the curvature of the superhelix to different angles of roll at each kind of dinucleotide step, i.e. an opening up of an angle by an increased separation on the minor-groove side. The main effect is due to a difference of about 3.degree. in roll values between AA/TT and other steps, together with a difference of about 1.degree. in the angle of helical twist: we deduce these values explicitly from some of the available data on gel-running. The scheme involves a simple calculation of the superhelical parameters for any given repeating sequence, and its gives a good correlation with all of the available data. We argue that these same base-step angular parameters are also consistent with observations from X-ray diffraction of crystallized oligomers, and particularly with the recent data on CGCA6GCG from Nelson et al. We are concerned here with the intrinsic curvature of unconstrained DNA, as distinct from the curvature of DNA in association with protein molecules; and this paper represents a first attempt at an absolute determination.