合成血铜复合体中的光诱导一氧化碳迁移
H Christopher Fry1, Andrew D Cohen, John P Toscano
1Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Journal of the American Chemical Society
|April 28, 2005
概括
来自合成血红铜复合体的光解离一氧化碳 (CO) 迅速与铜结合,然后转移回血红. 这种CO转移机制模仿了细胞染色体c氧化酶的活性位点.
科学领域:
- 生物有机化学 生物有机化学
- 摄影化学的使用.
- 频谱学是一种光谱学.
背景情况:
- 血铜复合物在生物系统中至关重要,特别是在细胞染色体c氧化酶中,用于气体运输和氧化还原反应.
- 了解联体动力学,如一氧化碳 (CO) 结合和释放,是阐明酶机制的关键.
- 合成模型为复杂的生物活性站点的功能机制提供了见解.
研究的目的:
- 为了研究一氧化碳 (CO) 解离和转移在合成血-CO/铜复合体中的动态.
- 为了比较合成复合体中的CO转移机制与细胞染色体c氧化酶的heme (a3) / Cu (b) 活性位点.
- 确定控制和铜部分之间的二氧化碳转移的动力学和热力学参数.
主要方法:
- 时间分辨率红外光谱 (TRIR) 用于监测CO分离和结合.
- 过渡吸收 (TA) 紫外线光谱法用于跟踪CO转移期间的索雷特波段.
- 对温度依赖的动态数据进行耳环分析,以计算激活度.
主要成果:
- 观察到二氧化碳从合成的血-二氧化碳/铜复合体, [((6) L) Fe (((II) ((CO)..Cu ((I) ] ((+) 的有效分离.
- 光解离二氧化碳暂时与铜中心结合,其速率常数为k(1) = 1.5 x 10(5) s(-1).
- 随后的CO从铜转移回血发生的速度常数k(2) = 1600s(-1),激活度为43.9kJ mol(-1).
结论:
- 该研究揭示了一种两步的CO转移机制,涉及暂时的铜结合,类似于细胞染色体c氧化酶.
- 在合成复合体中,CO与铜的分离似乎调节了小分子与血红素的结合.
- 这些发现为合成和生物系统相关的铜活性部位提供了有价值的机械洞察力.
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