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关于精氨酸中形交叉点的可访问性:素及其单质子和脱质子形式的素
Juan P Villabona-Monsalve1, Raquel Noria, Spiridoula Matsika
1Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México, 04510, D.F., México.
Journal of the American Chemical Society
|April 11, 2012
概括
从基DNA基中去除氨基组,例如素,可以显著缩短激发状态的寿命,使形交叉点更容易获得. 质子化和脱质子化场所也对这些动态产生了重要影响.
科学领域:
- 摄影化学的使用.
- 量子化学 是一个量子化学.
- 生物物理学的生物物理.
背景情况:
- 了解 purin DNA 基的兴奋状态动态对于破译它们的光化学行为和损伤潜力至关重要.
- 圆交点 (CI) 在分子的超快无辐射衰变中起着关键作用.
- 素和素是重要的纯素衍生物,在核酸和生物化学中具有重要意义.
研究的目的:
- 调查影响低素和素基态形交叉点可访问性的分子参数.
- 为了比较催化状态的动态的hypoxanthine和它的核酸酶因素与相关的基础,如关氨酸.
- 阐明结构修饰的作用,如氨基群存在/不存在和质子化/解质子化状态,在兴奋状态生命周期中.
主要方法:
- 使用五秒光上转换光谱法测量激发状态寿命.
- 在水和甲醇溶液中进行了实验.
- 进行了多参考扰动理论 (MRMP2) 和多参考配置相互作用 (MR-CIS) 计算,以分析电子激发和识别形交叉点.
主要成果:
- 中性低氨酸 tautomers 呈现超短激发状态寿命 (<0.2 ps),比关氨酸更短,表明由于缺乏氨基基组,更容易获得的CI.
- 单质子型低氨酸呈现了比特指数衰变,包括0.2ps以下的成分和1.1ps的成分.
- 与因诺辛和质子化形式相比,单次去质子化素的寿命显著更长 (19 ps),这归因于不同的去质子化部位和共振结构.
结论:
- 氨基基团的存在或不存在是决定激发状态动态和 purin 中 CI 可访问性的关键因素.
- 质子化和脱质子化状态对激发状态的生命周期有深远的影响,脱质子化部位尤其具有影响力.
- 计算和实验结果澄清了纯素中的微妙结构变化如何通过形交叉点来决定它们的光化学路径.
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