Detection of internal and overall dynamics of a two-atom-tethered spin-labeled DNA.
Detection of internal and overall dynamics of a two-atom-tethered spin-labeled DNA.
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检测双原子自旋标记 DNA 的内部和整体动态。
DOI：
10.1021/bi00028a040
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发表时间：
1995
期刊：
影响因子：
2.9
通讯作者：
Bobst,AM
中科院分区：
文献类型：
--
作者：
Keyes,RS;Bobst,AM
DNA运动由几个相互耦合的组件组成，这使得他们的研究变得困难。这项研究描述了一种在检测自旋标记核酸时通过EPR获得动力学信息的方法。分析是通过实现两个运动模型来完成的。第一个模型(即动态圆柱体模型)将自旋标记的螺旋看作一个扩散的圆柱体，其中包含由序参数表征的内部动力学。第二种模型(即基盘模型)提供了描述自旋标记碱基扩散的关联时间。在每个模型中，氮氧化物的运动既包括全球贡献，也包括内部贡献。动态柱面和基盘模拟四个含氮氧化合物通过两原子链结(DUMTA)-(Dt)7DUMTA-(Dt)7-(Da)15，[(Dt)7DUMTA(Dt)7]2-(Da)30，[(Dt)7DUMTA(Dt)7]3-(Da)45和[(Dt)7DUMTA(Dt)7]m-(Da)“连接在胸腺嘧啶核苷上。从动态圆柱体模拟中发现，内部运动的有序参数与螺旋长度无关(S=0.32±0.01)。以前对标记了五个原子的氮氧化物的DNA 26聚体和聚合物的碱基圆盘模拟似乎表明，z±只对内部动力学敏感。DUMTA标记DNA的基盘模拟结果表明，基盘关联时间的垂直分量(r±=
DNA motions consist of several components which couple, making their investigation difficult. This studydescribes an approach for obtaining dynamical information by EPR when spin-labeled nucleic acids are examined. The analysis is accomplished by implementing two motional models. The first model (ie, dynamic cylinder model) views the spin-labeled helix as a diffusing cylinder containing internal dynamics which are characterized by an order parameter. The second model (ie, base disk model) provides correlation times describing the diffusion of the spin-labeled base. In each model, the nitroxide motion consists of both global and internal contributions. Dynamic cylinder and base disk simulations of four duplexes containing nitroxides attached to thymidine by a two-atom tether (DUMTA)—(dT) 7DUMTA-(dT) 7-(dA) 15,[(dT) 7DUMTA (dT) 7] 2-(dA) 30,[(dT) 7DUMTA (dT) 7] 3-(dA) 45, and [(dT) 7DUMTA (dT) 7] m--(dA)„—demonstrate the useful application of this approach. From dynamiccylinder simulations, the order parameter for internalmotions is found to be independent of the helix length (S=0.32±0.01). Previous base disk simulations of a DNA 26mer and polymer labeled with a five-atom-tethered nitroxide seemed to indicate that z±was only sensitiveto internal dynamics. Results from base disk simulations of DUMTA-labeled DNA indicate that the perpendicular component of the base disk correlation time (r±=