缓冲器辅助的质子合电子转移在一个模型的-氨酸复合物中.
Hiroshi Ishikita1, Alexander V Soudackov, Sharon Hammes-Schiffer
1Department of Chemistry, 104 Chemistry Building, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Journal of the American Chemical Society
|August 21, 2007
概括
酸盐缓冲体,而不是水,在复合体中通过质子合电子转移 (PCET) 促进了铁基的产生. 这一发现澄清了生物重要过程中的关键步骤.
科学领域:
- 无机化学 无机化学
- 物理化学 物理化学
- 生物化学 生物化学
背景情况:
- 铁基生成在许多生物过程中至关重要.
- 了解像[Re(P-Y) ((phen) ((CO) 3PF6这样的有机金属复合物中激素形成的机制至关重要.
- 质子合电子转移 (PCET) 反应是化学和生物转换的基础.
研究的目的:
- 阐明[Re(P-Y) ((phen) ((CO) 3PF6复合体中铁基生成的机制.
- 研究不同质子受体 (水与酸盐缓冲区) 在PCET反应中的作用.
- 分析影响反应速率和动态同位素效应的因素.
主要方法:
- 多态连续理论被用来建模质子合电子转移 (PCET) 反应.
- 计算考虑了水和酸盐缓冲物种作为潜在的质子受体.
- 分析包括重组能量,反应自由能量,激活自由能量和和转移的振动合.
主要成果:
- 酸盐缓冲物种HPO4(2-) 被确定为有效的质子受体,成功地重现了实验中的pH依赖性和H/D动态同位素效应.
- 使用水作为质子接受器的模型被发现对这个系统来说在物理上是不合理的.
- 主导率贡献源于由于更大的振动合和重叠而导致非adiabatic向更高产品振动状态的过渡.
结论:
- 酸盐缓冲物种,特别是HPO4(2-),在研究的复合体的铁基生成机制中发挥着关键作用.
- 较小的质子捐助者-受体距离和有利的电子相互作用使酸盐比水更有效的质子受体.
- 这些发现提供了对基生成的基本见解,与各种生物系统相关.
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