Structural Basis for a Quadratic Relationship between Electronic Absorption and Electronic Paramagnetic Resonance Parameters of Type 1 Copper Proteins
Structural Basis for a Quadratic Relationship between Electronic Absorption and Electronic Paramagnetic Resonance Parameters of Type 1 Copper Proteins
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DOI：
10.1021/acs.inorgchem.0c01065
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发表时间：
2020-08-03
影响因子：
4.6
通讯作者：
Lu，Yi
中科院分区：
文献类型：
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作者：
Yu，Sheng-Song;Li，Jun-Jie;Lu，Yi
1型铜蛋白（Type 1 copper, T1Cu）在生物学中起着重要的电子传递作用，这主要是由于T1Cu中心的独特结构，这可以从其光谱性质上反映出来。先前的报道表明，在~ 450 nm处与~ 600 nm处的高电子吸光度比（R=A450/A600）与电子顺磁共振（EPR）中在z方向（Az）上的大铜（II）超细耦合之间存在相关性。然而，这种相关性并没有明确的物理意义，对于许多T1Cu中心受干扰的蛋白质也不成立。为了解决这一问题，在综合分析T1Cu蛋白的紫外可见吸收、EPR和结构参数的基础上，定义了一个具有分数SCyspseudo-σ到Cu（II）电荷转移跃迁强度的新参数r ‘ [A450/(A450+A600)]，并发现了r ’和azi之间的二次关系。我们可以发现r '与铜在His2Cys配体定义的三角平面上的位移以及nhis1 - cu - nhis2平面与scys - cu -轴向配体平面之间的夹角之间存在良好的相关性，为观察到的相关性提供了结构基础。这些发现和分析为深入了解T1Cu蛋白的光谱和电子特性提供了一个新的框架，这可能有助于更好地设计和应用这类重要的氧化还原和电子传递功能的蛋白质。
Type 1 copper (T1Cu) proteins play important roles in electron transfer in biology, largely due to the unique structure of the T1Cu center, which is reflected by its spectroscopic properties. Previous reports have suggested a correlation between a high ratio of electronic absorbance at ∼450 nm to that at ∼600 nm (R=A450/A600) and a large copper(II) hyperfine coupling in thezdirection (Az) in electron paramagnetic resonance (EPR). However, this correlation does not have a clear physical meaning, nor does it hold for many proteins with a perturbed T1Cu center. To address this issue, a new parameter ofR′ [A450/(A450+A600)] with a better physical meaning of a fractional SCyspseudo-σ to Cu(II) charge transfer transition intensity is defined and a quadratic relationship betweenR′ andAzis found on the basis of a comprehensive analysis of ultraviolet–visible absorption, EPR, and structural parameters of T1Cu proteins. We are able to find good correlations betweenR′ and the displacement of copper from the trigonal plane defined by the His2Cys ligands and the angle between the NHis1–Cu–NHis2plane and the SCys–Cu–axial ligand plane, providing a structural basis for the observed correlation. These findings and analyses provide a new framework for a deeper understanding of the spectroscopic and electronic properties of T1Cu proteins, which may allow better design and applications of this important class of proteins for redox and electron transfer functions.