Solvation effects on S K-edge XAS spectra of Fe-S proteins: normal and inverse effects on WT and mutant rubredoxin.
Solvation effects on S K-edge XAS spectra of Fe-S proteins: normal and inverse effects on WT and mutant rubredoxin.
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DOI：
10.1021/ja102807x
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发表时间：
2010-09-15
影响因子：
15
通讯作者：
Solomon, Edward I.
中科院分区：
文献类型：
--
作者：
Sun, Ning;Dey, Abhishek;Xiao, Zhiguang;Wedd, Anthony G.;Hodgson, Keith O.;Hedman, Britt;Solomon, Edward I.
对溶液和冻干形式的野生型Cp红氧还蛋白及其Cys->Ser突变体进行K边缘X射线吸收光谱（XAS）。对于野生型红氧还蛋白和其中内部半胱氨酸残基（C6或C39）被丝氨酸取代的突变体，观察到正常的溶剂效应，即，S共价性在冻干后增加。对于其中溶剂可接近的表面半胱氨酸残基被丝氨酸取代的突变体，S共价在冻干后降低，这是逆溶剂效应。密度泛函理论（DFT）的计算重现这些实验结果表明，正常的溶剂效应反映了共价性下降，由于溶剂氢键的表面硫醇和逆溶剂效应的结果从共价性补偿从内部硫醇。对于Cys->Ser取代，S共价性降低。计算表明，较强的键合相互作用的醇盐与铁相对于硫醇盐的Fe d轨道的能量增加，并减少其与剩余的半胱氨酸的键合相互作用。溶剂效应支持表面溶剂调节对电子转移的贡献，并且Cys->Ser结果为相关铁硫位点的性质变化提供了解释。
S K-edge X-ray Absorption Spectroscopy (XAS) was performed on wild type Cp rubredoxin and its Cys->Ser mutants in both solution and lyophilized forms. For wild type rubredoxin and for the mutants where an interior cysteine residue (C6 or C39) is substituted by serine, a normal solvent effect is observed, that is, the S covalency increases upon lyophilization. For the mutants where a solvent accessible surface cysteine residue is substituted by serine, the S covalency decreases upon lyophilization which is an inverse solvent effect. Density functional theory (DFT) calculations reproduce these experimental results and show that the normal solvent effect reflects the covalency decrease due to solvent H-bonding to the surface thiolates and that the inverse solvent effect results from the covalency compensation from the interior thiolates. With respect to the Cys->Ser substitution, the S covalency decreases. Calculations indicate that the stronger bonding interaction of the alkoxide with the Fe relative to that of thiolate increases the energy of the Fe d orbitals and reduces their bonding interaction with the remaining cysteines. The solvent effects support a surface solvent tuning contribution to electron transfer and the Cys->Ser result provides an explanation for the change in properties of related iron-sulfur sites with this mutation.
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影响因子：
15
作者：
HEDMAN, B;FRANK, P;HODGSON, KO
通讯作者：
HODGSON, KO
影响因子：
15
作者：
CZERNUSZEWICZ, RS;KILPATRICK, LK;SPIRO, TG
通讯作者：
SPIRO, TG
DOI：
10.1073/pnas.93.17.8836
发表时间：
1996-08-20
影响因子：
11.1
作者：
Dauter, Z;Wilson, KS;Meyer, J
通讯作者：
Meyer, J
影响因子：
15
作者：
Achim, C;Bominaar, EL;Münck, E
通讯作者：
Münck, E
影响因子：
4.6
作者：
Dey, A;Roche, CL;Solomon, EI
通讯作者：
Solomon, EI