在细胞染色体c氧化酶的功能模型中,光谱证据表明-超氧化物/Cu(I) 中间体
James P Collman1, Christopher J Sunderland, Katja E Berg
1Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA. jpc@stanford.edu
Journal of the American Chemical Society
|May 29, 2003
概括
研究人员开发了一种终端氧化酶模型. 纯铁和铁/铜模型出乎意料地形成了一个六坐标的血-超氧化物复合物,与典型的-氧化物中间体不同.
科学领域:
- 生物化学 生物化学
- 生物有机化学 生物有机化学
- 生物物理学的生物物理.
背景情况:
- 终端氧化酶,如细胞染色体c氧化酶,是细胞呼吸中的关键酶.
- 了解这些酶的活性位点是阐明电子转移机制的关键.
- 以前的模型经常在氧气结合后形成mu-peroxo中间体.
研究的目的:
- 创建一个新的超结构四甲氨酸模型,模仿终端氧化酶的活性位点.
- 为了研究Fe-only和双核Fe/Cu复合体中的氧 adduct形成.
- 为了比较氧结合特性与已知的血红素/铜酶中间体.
主要方法:
- 合成一个超结构的四甲氨酸与近位和远位的伊米达群.
- 光谱分析包括核磁共振 (NMR) 和电子磁共振 (EPR).
- 共振拉曼光谱与氧同位素标记 (16O2/18O2) 识别振动模式.
主要成果:
- 只有Fe的血红蛋白模型形成了一个六坐标的血红蛋白-超氧化物复合体,由二磁性NMR,EPR静音和特有的nuFe-O波段证明.
- 铁/复合体,铜位于海姆的上方,意外也形成了一个超氧化物 adduct.
- 这些发现与通常在双核/铜复合体中观察到的mu-peroxo中间体形成鲜明对比.
结论:
- 开发的超结构氨酸模型有效地模仿了终端氧化酶活性位点的各个方面.
- 在Fe-only和Fe/Cu系统中形成超氧化的形成为氧气激活机制提供了新的见解.
- 这项研究挑战了以前关于相关双核复合体中氧中间体形成的假设.
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