Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Rosario, S2002LRK Rosario, Argentina.
Proc Natl Acad Sci U S A. 2012 Oct 23;109(43):17348-53. doi: 10.1073/pnas.1204251109. Epub 2012 Oct 10.
Electron transfer is the simplest chemical reaction and constitutes the basis of a large variety of biological processes, such as photosynthesis and cellular respiration. Nature has evolved specific proteins and cofactors for these functions. The mechanisms optimizing biological electron transfer have been matter of intense debate, such as the role of the protein milieu between donor and acceptor sites. Here we propose a mechanism regulating long-range electron transfer in proteins. Specifically, we report a spectroscopic, electrochemical, and theoretical study on WT and single-mutant Cu(A) redox centers from Thermus thermophilus, which shows that thermal fluctuations may populate two alternative ground-state electronic wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways. These findings suggest a unique role for alternative or "invisible" electronic ground states in directional electron transfer. Moreover, it is shown that this energy gap and, therefore, the equilibrium between ground states can be fine-tuned by minor perturbations, suggesting alternative ways through which protein-protein interactions and membrane potential may optimize and regulate electron-proton energy transduction.
电子转移是最简单的化学反应，构成了多种生物过程的基础，如光合作用和细胞呼吸。大自然已经进化出了专门的蛋白质和辅因子来完成这些功能。优化生物电子转移的机制一直是激烈争论的话题，例如供体和受体位点之间的蛋白质环境的作用。在这里，我们提出了一种调节蛋白质中长程电子转移的机制。具体来说，我们报告了来自嗜热菌的 WT 和单突变 Cu(A) 氧化还原中心的光谱、电化学和理论研究，结果表明，热波动可能会占据两种替代的基态电子波函数，分别优化了电子的进入和退出，分别通过两条不同的、几乎垂直的路径。这些发现表明，替代或“不可见”的电子基态在定向电子转移中具有独特的作用。此外，研究表明，这个能隙，因此，两种基态之间的平衡可以通过微小的扰动进行微调，这表明蛋白质-蛋白质相互作用和膜电位可能通过替代方式优化和调节电子-质子能量传递。
