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在铁-原氨酸-IX模型化合物中,在胺中进行质子合电子转移反应
Jeffrey J Warren1, James M Mayer
1Beckman Institute, California Institute of Technology, MC 139-74, Pasadena, California 91125-0001, USA. jwarren@caltech.edu
Journal of the American Chemical Society
|April 29, 2011
概括
这项研究开发了一种模型系统,其中 propionate 作为唯一的质子位点. 这项研究突出了血红蛋白酸盐作为血红蛋白中质联电子转移反应的潜在活性场所.
科学领域:
- 生物有机化学 生物有机化学
- 生物物理化学 生物物理化学
- 化学物理 化学物理
背景情况:
- 血红蛋白在生物氧化还原过程中起着至关重要的作用.
- 了解质子合电子转移 (PCET) 的机制对于破译这些生物功能至关重要.
- 模型系统对于分离和研究复杂的生物分子中的特定化学事件至关重要.
研究的目的:
- 开发一个简化的血红素模型系统,其中血红素是独家的质子捐赠者/接受者.
- 为了研究涉及这个模型系统的质子合电子转移 (PCET) 反应.
- 评估 propionates 在蛋白 PCET/CPET 活性位点中的潜在作用.
主要方法:
- 使用原氨酸IX-单甲基 (PPIX(MME)) 和N-甲基胺 (MeIm) 来创建一个血模型.
- 在使用各种降解剂和氧化剂,如酸盐衍生物,TEMPOH,化,TEMPO和化等酸溶剂中检查了PCET反应.
- 确定平衡常数,pK(a) 和E(1/2) 值来计算有效的债券解离自由能量 (BDFE).
主要成果:
- 成功建立了一个血模型系统 (PPIX(MME))Fe(III) ((MeIm) ((2) -propionate (Fe(III) ~ CO(2)) 用酸作为唯一的质子位点.
- 通过电子和质子转移介导的Fe(III) ~CO(2) 和Fe(II) ~CO(2) H形式之间的可逆回氧反应.
- 计算出一个有效的BDFE为67.8±0.6 kcalmol{-1) 的Fe{II) ~CO{2) H.
- 确定了铁中心的电子转移和远程 propionate 的质子转移.
- 提供了与TEMPOH和甲酸盐衍生物反应中的协同质子电子转移 (CPET) 机制的证据.
结论:
- 血红素酸盐可以作为PCET反应中的关键质子转移点.
- 开发的血模型系统有效地模仿了生物系统中PCET的各个方面.
- 血红蛋白酸盐应被认为是参与PCET/CPET过程的血红蛋白活性部位中的潜在关键成分.
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