Scott R A, Schwartz J R, Cramer S P
Biochemistry. 1986 Sep 23;25(19):5546-55. doi: 10.1021/bi00367a030.
Copper K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the structural details of the coordination environment of the copper sites in eight resting-state samples of beef heart cytochrome c oxidase prepared by different methods. The unusual position and structure of the resting-state copper edge spectrum can be adequately explained by the presence of sulfur-containing ligands, with a significant amount of S----Cu(II) charge transfer (i.e., a covalent site). Quantitative curve-fitting analysis of the copper extended X-ray absorption fine structure (EXAFS) data indicates similar average first coordination spheres for all resting-state samples, regardless of preparation method. The average coordination sphere (per 2 coppers) mainly consists of 6 +/- 1 nitrogens or oxygens at an average Cu-(N,O) distance of 1.99 +/- 0.03 A and 2 +/- 1 sulfurs at an average Cu-S distance of 2.28 +/- 0.02 A. Quantitative curve-fitting analysis of the outer shell of the copper EXAFS indicates the presence of a Cu...Fe interaction at a distance of 3.00 +/- 0.03 A. Proposed structures of the two copper sites based on these and other spectroscopic results are presented, and differences between our results and those of other published copper XAS studies [Powers, L., Chance, B., Ching, Y., & Angiolillo, P. (1981) Biophys. J. 34, 465-498] are discussed.
铜 K 边 X 射线吸收光谱（XAS）已被用于研究通过不同方法制备的八个静息态牛心细胞色素 c 氧化酶样品中铜位点配位环境的结构细节。静息态铜边光谱的异常位置和结构可以通过含硫配体的存在得到充分解释，存在大量的 S----Cu(II)电荷转移（即一个共价位点）。对铜扩展 X 射线吸收精细结构（EXAFS）数据的定量曲线拟合分析表明，所有静息态样品的平均第一配位层相似，与制备方法无关。平均配位层（每 2 个铜原子）主要由 6±1 个氮原子或氧原子组成，平均 Cu-(N,O)距离为 1.99±0.03 Å，以及 2±1 个硫原子，平均 Cu-S 距离为 2.28±0.02 Å。对铜 EXAFS 外壳的定量曲线拟合分析表明，在 3.00±0.03 Å 的距离处存在 Cu...Fe 相互作用。基于这些及其他光谱结果提出了两个铜位点的结构，并讨论了我们的结果与其他已发表的铜 XAS 研究结果[Powers, L., Chance, B., Ching, Y., & Angiolillo, P. (1981) Biophys. J. 34, 465 - 498]之间的差异。
