We combine experimental and computational methods to address the anomalous kinetics of long-range electron transfer (ET) in mutants of Pseudomonas aeruginosa azurin. ET rates and driving forces for wild type (WT) and three N47X mutants (X = L, S, and D) of Ru(2,2′-bipyridine)₂ (imidazole)(His83) azurin are reported. An enhanced ET rate for the N47L mutant suggests either an increase of the donor–acceptor (DA) electronic coupling or a decrease in the reorganization energy for the reaction. The underlying atomistic features are investigated using a recently developed nonadiabatic molecular dynamics method to simulate ET in each of the azurin mutants, revealing unexpected aspects of DA electronic coupling. In particular, WT azurin and all studied mutants exhibit more DA compression during ET (>2 Å) than previously recognized. Moreover, it is found that DA compression involves an extended network of hydrogen bonds, the fluctuations of which gate the ET reaction, such that DA compression is facilitated by transiently rupturing hydrogen bonds. It is found that the N47L mutant intrinsically disrupts this hydrogen-bond network, enabling particularly facile DA compression. This work, which reveals the surprisingly fluctional nature of ET in azurin, suggests that hydrogen-bond networks can modulate the efficiency of long-range biological ET.

我们结合实验和计算方法来解决铜绿假单胞菌天青蛋白突变体中远程电子转移（ET）的异常动力学。野生型（WT）和Ru（2,2'-联吡啶）_2的三个N47X突变体（X = L，S和D）的ET速率和驱动力据报道有（咪唑）（His83）天青蛋白。N47L突变体的ET速率提高表明，供体-受体（DA）电子偶联增加或反应的重组能降低。使用最近开发的非绝热分子动力学方法研究潜在的原子特征，以模拟每个天青蛋白突变体中的ET，揭示了DA电子偶联的意外方面。特别是，WT天青蛋白和所有研究的突变体在ET（> 2Å）期间显示出比以前公认的更高的DA压缩率。此外，发现DA压缩涉及氢键的扩展网络，该氢键的波动控制ET反应，从而通过瞬时破坏氢键来促进DA压缩。发现N47L突变体固有地破坏了该氢键网络，从而使得特别容易的DA压缩。这项工作揭示了天青蛋白中ET的令人惊讶的迁移性质，表明氢键网络可以调节远程生物ET的效率。