相关实验视频
通过人类硫胺酸酸酶对提米丁水解的过渡状态分析
Phillip A Schwartz1, Mathew J Vetticatt, Vern L Schramm
1Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
Journal of the American Chemical Society
|September 1, 2010
概括
人类胆氨酸酸化酶 (hTP) 促进胆氨酸稳态和血管生成. 这项研究揭示了hTP的存在.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 化学动力学 化学动力学
背景情况:
- 人类胆氨酸酸化酶 (hTP) 调节胆氨酸稳态,并与血管生成有关.
- 在缺乏酸盐的情况下,hTP催化了提米丁的水解性脱皮里米丁化,将其转化为提胺和2-脱氧利.
- 了解hTP的催化机制对于其在生物过程中的作用至关重要.
研究的目的:
- 描述由人类胺酸酶 (hTP) 催化的水解性脱皮里米定化反应的过渡状态.
- 阐明反应机制,并确定因缺少酸盐而导致的关键催化残留物.
- 为了比较水解机制与之前报告的解反应.
主要方法:
- 从葡萄糖或 (脱氧) 核糖中合成同位素丰富的蒂米丁.
- 测量多种动态同位素效应 (KIEs) 使用各种标记的thymidines.
- 使用密度函数理论 (DFT) 建模过渡状态的计算分析.
主要成果:
- 动态同位素效应测量揭示了一种阶段性机制,涉及早期形成2 - 脱氧化介质.
- 对于水对这种中间体的核友性攻击,观察到一个重要的能量屏障.
- 密度函数理论计算确定了His116作为一个潜在的催化基,激活水核友.
结论:
- 水溶性反应通过一个阶段性机制进行,与溶性反应的协同机制不同.
- 胺脱离组的激活发生在不需要酸盐的情况下.
- 该研究提供了过渡状态的详细模型,涉及His116的催化作用,并表明了脱氧的3'-endo构成.
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