Long-range protein electron transfer observed at the single-molecule level:: In situ mapping of redox-gated tunneling resonance
Long-range protein electron transfer observed at the single-molecule level:: In situ mapping of redox-gated tunneling resonance
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DOI：
10.1073/pnas.0508257102
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发表时间：
2005-11-08
影响因子：
11.1
通讯作者：
Ulstrup, J
中科院分区：
文献类型：
--
作者：
Chi, QJ;Farver, O;Ulstrup, J
基于分子布线自组装原理，设计了一种由蓝铜蛋白天青、隧穿势垒桥和金单晶电极组成的仿生远程电子转移系统.该系统在准生物环境中具有足够的稳定性和灵敏度，适合于在纳米级和单分子水平上详细观察长距离蛋白质界面ET。由于天青蛋白位于明确可识别的固定位点，方向控制良好，ET构型与生物ET平行。电子隧穿是非绝热的，速率常数显示隧穿特征，在H_2O和D_2O中的距离衰减因子分别为0.83和0.91埃。氧化还原门控隧穿共振是通过电化学扫描隧道显微镜在单分子水平上原位观察到的，表现出对氧化还原电位的不对称依赖性。最大共振出现在平衡氧化还原电位的天青与开/关电流比约为9。模拟分析，基于一个两步界面ET模型的扫描隧道显微镜氧化还原过程中，进行了合理理解的ET机制，并提供定量信息。
A biomimetic long-range electron transfer (ET) system consisting of the blue copper protein azurin, a tunneling barrier bridge, and a gold single-crystal electrode was designed on the basis of molecular wiring self-assembly principles. This system is sufficiently stable and sensitive in a quasi-biological environment, suitable for detailed observations of long-range protein interfacial ET at the nanoscale and single-molecule levels. Because azurin is located at clearly identifiable fixed sites in well controlled orientation, the ET configuration parallels biological ET. The ET is nonadiabatic, and the rate constants display tunneling features with distance-decay factors of 0.83 and 0.91 angstrom(-1) in H2O and D2O, respectively. Redox-gated tunneling resonance is observed in situ at the single-molecule level by using electrochemical scanning tunneling microscopy, exhibiting an asymmetric dependence on the redox potential. Maximum resonance appears around the equilibrium redox potential of azurin with an on/off current ratio of approximate to 9. Simulation analyses, based on a two-step interfacial ET model for the scanning tunneling microscopy redox process, were performed and provide quantitative information for rational understanding of the ET mechanism.