通过2D-EPR揭示的"基-fff"cob(II) 亚胺和相关的co(II) -corrinates中的轴性溶剂协调
Sabine Van Doorslaer1, Gunnar Jeschke, Boris Epel
1Laboratory of Physical Chemistry, ETH Hönggerberg, CH-8093 Zurich, Switzerland.
Journal of the American Chemical Society
|May 8, 2003
概括
(II) 酸盐和 (II) 胺中间体在协酶B12反应中一样,表现出依赖溶剂的结构. 先进的EPR和ENDOR技术揭示了由溶剂特性影响的轴联结和协调变化.
科学领域:
- 协调化学 协调化学
- 生物有机化学 生物有机化学
- 频谱学是一种光谱学.
背景情况:
- (II) 酸盐是辅酶B12催化反应中的关键中间体.
- 了解它们在溶液中的结构是阐明酶机制的关键.
- (II) 的溶解性允许对 (II) 酸盐的溶剂作用进行受控研究.
研究的目的:
- 为了研究 (II) 角酸盐,特别是 (II) 和 (II) (B12r) 的溶液结构.
- 为了确定的协调状态 (轴联结),在各种溶剂中化.
- 探索溶剂性质和相变对 (II) 酸盐结构的影响.
主要方法:
- 使用了连续波 (CW) 和脉冲电子磁共振 (EPR) 光谱的组合.
- 在各种微波频率上使用脉冲ENDOR (电子核双共振).
- 支持数据解释与密度函数理论 (DFT) 计算.
主要成果:
- 提供了明确的证据,证明了在不同溶剂中对Cob (II) 和基离Cob (II) (B12r) 的轴联.
- 证明了EPR参数 (g值,超精密合) 是溶剂结合的敏感指标.
- 观察到甲醇中Cob (II) 的温度依赖的结构变化,由于甲醇的相位过渡,从100K以下的5到6协调过渡.
结论:
- 溶剂特性显著影响了 (II) 角酸盐的协调结构.
- 溶液中的乙烯和基离子B12r的协调行为反映了它们的电子结构.
- 溶液研究与蛋白质嵌入式辅助因子之间的比较需要仔细考虑溶剂效应.
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