Dramatic Electronic Perturbations of CuA Centers via Subtle Geometric Changes.
Dramatic Electronic Perturbations of CuA Centers via Subtle Geometric Changes.
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通过微妙的几何变化对 CuA 中心进行剧烈的电子扰动。
DOI：
10.1021/jacs.8b12335
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发表时间：
2019
影响因子：
15
通讯作者：
Vila,AlejandroJ
中科院分区：
文献类型：
--
作者：
Leguto,AlcidesJ;Smith,MeghanA;Morgada,MarcosN;Zitare,UlisesA;Murgida,DanielH;Lancaster,KyleM;Vila,AlejandroJ
CuA是末端血红素-铜氧化酶的双核铜位点，作为电子进入口。在氧化形式中，CuA是一种混合价对，其电子结构可以使用具有两个最小值σu* 和πu的势能面来描述，这两个最小值在室温下是不稳定的。我们报告说，在双核金属辅因子的第一和第二协调领域的突变可以结合在一个添加剂的方式来调整的能隙，因此，相对人口的两个最低的躺状态。一系列设计的突变体跨越σu*/π u能隙范围从900到13 cm-1。最小的间隙对应于具有有效简并基态的变体。所有工程化位点保留了该金属中心的混合价特征和电子转移功能。Cu-Cu距离的增加小于0.06 μ m会使σu*/π u能隙改变近2个数量级，更长的距离会引发更大的π u态。这种情况与合成系统形成鲜明对比，因为模型化合物需要在Cu-Cu距离上延长0.5 μ m以稳定π状态。这些发现表明，蛋白质环境的严格控制允许CuAsites的电子结构发生剧烈扰动，并伴有微小的几何变化。
CuAis a binuclear copper site acting as electron entry port in terminal heme-copper oxidases. In the oxidized form, CuAis a mixed valence pair whose electronic structure can be described using a potential energy surface with two minima, σu* and πu, that are variably populated at room temperature. We report that mutations in the first and second coordination spheres of the binuclear metallocofactor can be combined in an additive manner to tune the energy gap and, thus, the relative populations of the two lowest-lying states. A series of designed mutants span σu*/πuenergy gaps ranging from 900 to 13 cm–1. The smallest gap corresponds to a variant with an effectively degenerate ground state. All engineered sites preserve the mixed-valence character of this metal center and the electron transfer functionality. An increase of the Cu–Cu distance less than 0.06 Å modifies the σu*/πuenergy gap by almost 2 orders of magnitude, with longer distances eliciting a larger population of the πustate. This scenario offers a stark contrast to synthetic systems, as model compounds require a lengthening of 0.5 Å in the Cu–Cu distance to stabilize the πustate. These findings show that the tight control of the protein environment allows drastic perturbations in the electronic structure of CuAsites with minor geometric changes.