Power of the Secondary Sphere: Modulating Hydrogenase Activity in Nickel-Substituted Rubredoxin
Power of the Secondary Sphere: Modulating Hydrogenase Activity in Nickel-Substituted Rubredoxin
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第二球体的力量：调节镍取代红红还蛋白中的氢化酶活性
DOI：
10.1021/acscatal.9b01720
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发表时间：
2019
期刊：
影响因子：
12.9
通讯作者：
Shafaat, Hannah S.
中科院分区：
文献类型：
--
作者：
Slater, Jeffrey W.;Marguet, Sean C.;Gray, Michelle E.;Monaco, Haleigh A.;Sotomayor, Marcos;Shafaat, Hannah S.
已知次级球体相互作用会显着影响生物系统以及合成分子催化剂内的催化速率。[NiFe]氢化酶在复杂的配位环境中以高周转率氧化并产生分子氢。镍取代rubredoxin（NiRd）已被开发为一个功能，蛋白质为基础的模拟[NiFe]氢化酶，提供了一个机会，了解二级配位环境对质子还原活性的影响。在这项工作中，一系列合理设计的突变体产生的外球相互作用对催化的影响进行了研究。该库的特点是使用定量蛋白膜电化学，光谱学，X射线晶体学，和分子动力学模拟。改变次级球残基调制的镍和铁结合rubredoxin蛋白的氧化还原活性，改变氢键网络，并扰乱溶剂的活性位点，这与催化营业额频率。对反应性的影响取决于突变位点，并且当与晶体学和计算分析相结合时，暗示镍配位半胱氨酸残基之一为质子化的机械相关位点。引入羧酸残基，模仿发现在[NiFe]氢化酶，显着增加整体催化速率，可能通过安装质子转移途径进入活性位点。突变体构建体内的表观周转频率范围为15至500 s-1，而不会引起超电位的显著变化，并且许多突变体打破了通常在小分子系统中看到的催化速率和超电位之间的典型比例关系。这些结果表明，人工金属酶，NiRd的产氢活性的配位环境的实质性影响，并突出分子催化剂内的这种相互作用的重要性。
Secondary sphere interactions are known to significantly impact catalytic rates within biological systems as well as synthetic molecular catalysts. The [NiFe] hydrogenase enzymes oxidize and produce molecular hydrogen at high turnover rates within a complex coordination environment. Nickel-substituted rubredoxin (NiRd) has been developed as a functional, protein-based mimic of the [NiFe] hydrogenase, providing an opportunity to understand the influence of the secondary coordination environment on proton reduction activity. In this work, a rationally designed series of mutants was generated to study the effects of outer-sphere interactions on catalysis. This library was characterized using quantitative protein film electrochemistry, optical spectroscopy, X-ray crystallography, and molecular dynamics simulations. Changing the secondary sphere residues modulates the redox activity of the nickel- and iron-bound rubredoxin proteins, alters the hydrogen-bonding network, and perturbs solvent accessibility of the active site, which correlates with catalytic turnover frequency. The effects on reactivity are dependent on the site of mutation and, when coupled to crystallographic and computational analyses, implicate one of the nickel-coordinating cysteine residues as the mechanistically relevant site of protonation. Introduction of a carboxylate residue, mimicking that found in the [NiFe] hydrogenase, significantly increases the overall catalytic rate, likely through installation of a proton transfer pathway into the active site. Apparent turnover frequencies within the mutant constructs range from 15 to 500 s–1without imparting significant variation in overpotential, and many mutants break the typical scaling relationship between catalytic rates and overpotential that is often seen in small-molecule systems. These results demonstrate the substantial impact of the coordination environment on the hydrogen-producing activity of the artificial metalloenzyme, NiRd, and highlight the importance of such interactions within molecular catalysts.
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影响因子：
3.2
作者：
Kraemer, Tobias;Kamp, Mario;Neese, Frank
通讯作者：
Neese, Frank
影响因子：
5.4
作者：
Grove, Laurie E.;Brunold, Thomas C.
通讯作者：
Brunold, Thomas C.
[NiFe]-氢化酶中的质子途径：理论研究
DOI：
--
发表时间：
2008
期刊：
Proteins: Structure, Function, and Bioinformatics
影响因子：
--
作者：
V. Teixeira;C. M. Soares;A. Baptista
通讯作者：
A. Baptista
DOI：
--
发表时间：
2012
期刊：
--
影响因子：
--
作者：
Ryan L. Shook;A. Borovik
通讯作者：
Ryan L. Shook;A. Borovik
影响因子：
62.1
作者：
Schilter, David;Camara, James M.;Huynh, Mioy T.;Hammes-Schiffer, Sharon;Rauchfuss, Thomas B.
通讯作者：
Rauchfuss, Thomas B.