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在DNA中的三氧三角离子间隙:结合,电子转移,X射线晶体学和电子结构
Jóhannes Reynisson1, Gary B Schuster, Sheldon B Howerton
1Schools of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Journal of the American Chemical Society
|February 20, 2003
概括
三氧三角离子 (TOTA(+)) 插入DNA,在辐射时引起大规模结构变化和链裂变. 它的方向受到DNA骨干相互作用的影响,而不是直接的电荷转移.
科学领域:
- 生物物理化学 生物物理化学
- 结构生物学 结构生物学
- 计算化学计算化学
背景情况:
- 三氧三角离子 (TOTA(+)) 是一种已知可以插入DNA的平面分子.
- 间隔通常涉及基对之间的堆叠,改变DNA结构.
- 之前的研究表明,TOTA(+) 可以在光刺激时诱导DNA损伤.
研究的目的:
- 为了阐明TOTA的结构和电子相互作用 (((+) 在DNA复合体内插入.
- 了解由光激发的TOTA引发的DNA链裂变的机制.
- 研究电子结构和环境因素在TOTA(+) -DNA结合中的作用.
主要方法:
- 在d[CGATCG](2) DNA复合体中插入的TOTA的X射线晶体学.
- 电子结构计算 (DFT) 用于分析轨道相互作用和电荷分布.
- 对DNA结构参数 (螺旋上升,方向) 和分子间相互作用的分析.
主要成果:
- X射线结构显示,在TOTA (((+) 间隙时,DNA螺旋上升的显著延伸.
- TOTA(+) 取向是由与DNA骨干原子的键决定的.
- 电子结构计算显示没有从DNA到TOTA的直接电荷转移;环境因素至关重要.
- 计算表明,间腔的极化和电子密度在TOTA周围的再分配.
结论:
- TOTA(+) 间隙诱导大量的DNA结构扭曲,主要影响螺旋式上升.
- 在调节TOTA(+) 和DNA电子状态方面,DNA骨干相互作用,水和 counterions 起着至关重要的作用.
- 观察到的DNA裂变很可能是光诱导的基离子形成和随后的化学反应的后果,受极化介质环境的影响.
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