有证据表明,氧化物在二水解中直接受到氧化物的攻击
Adam G Cassano1, Vernon E Anderson, Michael E Harris
1Center for RNA Molecular Biology and Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA.
Journal of the American Chemical Society
|September 13, 2002
概括
氧化在酸水解中充当直接核友,而不是一般基. 这项研究使用同位素效应来确认氧化物.
科学领域:
- 生物化学 生物化学
- 化学动力学 化学动力学
背景情况:
- 基溶解在生物过程中至关重要.
- 核在这些反应中的作用仍然不完全理解.
研究的目的:
- 为了阐明氧化物在蒂米丁-5'-p-尼托菲尼尔酸盐水解中的机制.
- 为了确定氧化物是否作为核友或一般基.
主要方法:
- 测量了溶剂同位素效应 (D2Ok).
- 分析了离子强度的影响.
- 确定了18O同位素对溶剂核 (18knuc) 的影响.
主要成果:
- 稍微反向的D2Ok表明在过渡状态中没有质子转移.
- 氧化水表现出显著的α效应,表明氧化离子的核友性攻击.
- 氧化物和氧化物的不可分辨的离子强度依赖性表明了共享的机制.
- 18knuc超出了平衡18O同位素效应,支持氧化物直接核友性攻击.
结论:
- 数据强烈支持氧化物在二水解中的直接核友性攻击.
- 18O同位素效应的大量动力成分表明,在过渡状态下,键序的形成是最小的.
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