Counterion distribution around DNA probed by solution X-ray scattering
Counterion distribution around DNA probed by solution X-ray scattering
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DOI：
10.1103/physrevlett.90.188103
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发表时间：
2003-05-09
影响因子：
8.6
通讯作者：
Pollack, L
中科院分区：
文献类型：
--
作者：
Das, R;Mills, TT;Pollack, L
反离子气氛凝聚在带电的生物聚合物上，强烈地影响它们的物理性质和生物功能，但很难在实验上量化。本文利用小角x射线散射技术，对溶液中DNA双螺旋周围的单价和二价反离子气氛进行了探测。通过异常（共振）x射线散射和交换离子身份调制离子散射因子，产生由于周围离子与DNA的空间相关性而产生的散射信号的直接测量。数据的质量首次允许对从生物学相关分子的原子尺度模型计算的扩展反离子分布进行定量测试。
Counterion atmospheres condensed onto charged biopolymers strongly affect their physical properties and biological functions, but have been difficult to quantify experimentally. Here, monovalent and divalent counterion atmospheres around DNA double helices in solution are probed using small-angle x-ray scattering techniques. Modulation of the ion scattering factors by anomalous (resonant) x-ray scattering and by interchanging ion identities yields direct measurements of the scattering signal due to the spatial correlation of surrounding ions to the DNA. The quality of the data permit, for the first time, quantitative tests of extended counterion distributions calculated from atomic-scale models of biologically relevant molecules.