Effect of surface charges on the rates of intermolecular electron-transfer between de novo designed metalloproteins.
Effect of surface charges on the rates of intermolecular electron-transfer between de novo designed metalloproteins.
复制标题
表面电荷对从头设计的金属蛋白之间分子间电子转移速率的影响。
DOI：
10.1021/bi011156u
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发表时间：
2001
期刊：
影响因子：
2.9
通讯作者：
Ogawa,MY
中科院分区：
文献类型：
--
作者：
Kornilova,AY;Wishart,JF;Ogawa,MY
从头设计的卷曲螺旋金属蛋白的制备，使用静电相互作用来控制其构象和双分子电子转移性能。标题蛋白以[Ru（trpy）（bpy）-KK（37-mer）]和[Ru（NH 3）5-EE（37-mer）]多肽的卷曲螺旋异二聚体形式存在，其通过螺旋间静电吸引形成。圆二色性研究表明，该静电异二聚体的Kd = 0.19 ± 0.03 μM，在高浓度下为96%螺旋。研究了属于不同静电二聚体的[Ru（NH3）5-H21]2+电子给体和[Ru（trpy）（bpy）-H21]3+电子受体的络合物间电子转移反应。所设计的金属蛋白的一个重要特征是它的两个阳离子氧化还原中心嵌入蛋白质表面具有相反的电荷。因此，RuII（NH3）5-H21位点位于使其带正电的卷曲螺旋的一条链的表面上，并且RuIII（trpy）（bpy）-H21位点位于带负电的另一条链的表面上。随着离子强度从0.01 M增加到0.20 M，分子间电子转移速率从（1.9 ± 0.4）× 107 M-1 s-1增加到（3.7 ± 0.5）× 107 M-1 s-1。这表明钌中心之间的静电排斥主导了这些反应的动力学。然而，卷曲螺旋中带相反电荷的蛋白质表面的存在产生了静电识别结构域，其基本上改善了这种排斥的效果。
A de novo designed coiled-coil metalloprotein was prepared that uses electrostatic interactions to control both its conformational and bimolecular electron-transfer properties. The title protein exists as a coiled-coil heterodimer of the [Ru(trpy)(bpy)-KK(37-mer)] and [Ru(NH3)5-EE(37-mer)] polypeptides which is formed by interhelix electrostatic attractions. Circular dichroism studies show that the electrostatic heterodimer hasKd= 0.19 ± 0.03 μM and is 96% helical at high concentrations. Intercomplex electron-transfer reactions were studied that involve the [Ru(NH3)5-H21]2+electron-donor and the [Ru(trpy)(bpy)-H21]3+electron-acceptor belonging to different electrostatic dimers. An important feature of the designed metalloprotein is its two cationic redox centers embedded within protein surfaces having opposite charge. Thus, the RuII(NH3)5-H21 site was placed on the surface of one chain of the coiled-coil which was made to be positively charged, and the RuIII(trpy)(bpy)-H21 site was placed on the surface of the other chain which was negatively charged. The rates of intermolecular electron-transfer increased from (1.9 ± 0.4) × 107M-1s-1to (3.7 ± 0.5) × 107M-1s-1as the ionic strength was increased from 0.01 to 0.20 M. This indicates that the electrostatic repulsion between the ruthenium centers dominates the kinetics of these reactions. However, the presence of the oppositely charged protein surfaces in the coiled-coils creates an electrostatic recognition domain that substantially ameliorates the effects of this repulsion.