Spectroscopic and density functional theory studies of the blue-copper site in M121SeM and C112SeC azurin: Cu-Se versus Cu-S bonding.
Spectroscopic and density functional theory studies of the blue-copper site in M121SeM and C112SeC azurin: Cu-Se versus Cu-S bonding.
复制标题
DOI：
10.1021/ja076495a
复制
发表时间：
2008-03
影响因子：
15
通讯作者：
R. Sarangi;S. I. Gorelsky;L. Basumallick;H. Hwang;R. Pratt;T. Stack;Yi Lu;K. Hodgson;B. Hedman;E. Solomon
中科院分区：
文献类型：
--
作者：
R. Sarangi;S. I. Gorelsky;L. Basumallick;H. Hwang;R. Pratt;T. Stack;Yi Lu;K. Hodgson;B. Hedman;E. Solomon
利用X射线K边吸收光谱、紫外-可见吸收光谱、磁圆二色性（MCD）和共振拉曼光谱研究了WT、M121 SeM和C112 SeC铜绿假单胞菌（P.a）天青蛋白的电子结构差异。WT和M121 SeM天青和CuII-硫醚模型复合物的S K-边XAS的比较表明，蓝铜（BC）网站的基态波函数中的38% S字符仅反映了Cu-SCys键。WT和C112 SeC天青蛋白的共振拉曼（rR）数据为WT天青蛋白中Cu-SCys伸缩和半胱氨酸变形模式之间的运动学耦合提供了直接证据，这导致BC位点的rR光谱中的多个特征。WT、M121 SeM和C112 SeC的紫外-可见吸收和MCD数据给出了非常相似的C 0/D 0比，表明C项MCD强度机制涉及Cu中心的自旋轨道耦合（SOC）。光谱数据结合密度泛函理论（DFT）计算表明，SCys和SeCys在其各自的键长为2.1和2.3 A处与Cu具有相似的共价相互作用。这反映了硫/硒配体片段中S和Se的相似电负性，并解释了WT和C112 SeC天青之间的强烈光谱相似性。
S K-edge X-ray absorption, UV-vis absorption, magnetic circular dichroism (MCD), and resonance Raman spectroscopies are used to investigate the electronic structure differences among WT, M121SeM, and C112SeC Pseudomonas aeruginosa (P.a) azurin. A comparison of S K-edge XAS of WT and M121SeM azurin and a CuII-thioether model complex shows that the 38% S character in the ground state wave function of the blue-copper (BC) sites solely reflects the Cu-SCys bond. Resonance Raman (rR) data on WT and C112SeC azurin give direct evidence for the kinematic coupling between the Cu-SCys stretch and the cysteine deformation modes in WT azurin, which leads to multiple features in the rR spectrum of the BC site. The UV-vis absorption and MCD data on WT, M121SeM, and C112SeC give very similar C0/D0 ratios, indicating that the C-term MCD intensity mechanism involves Cu-centered spin-orbit coupling (SOC). The spectroscopic data combined with density functional theory (DFT) calculations indicate that SCys and SeCys have similar covalent interactions with Cu at their respective bond lengths of 2.1 and 2.3 A. This reflects the similar electronegativites of S and Se in the thiolate/selenolate ligand fragment and explains the strong spectroscopic similarities between WT and C112SeC azurin.