Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China.
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
Adv Sci (Weinh). 2023 Oct;10(29):e2302670. doi: 10.1002/advs.202302670. Epub 2023 Aug 16.
Electroactive microbial cells have evolved unique extracellular electron transfer to conduct the reactions via redox outer-membrane (OM) proteins. However, the electron transfer mechanism at the interface of OM proteins and nanomaterial remains unclear. In this study, the mechanism for the electron transfer at biological/inorganic interface is investigated by integrating molecular modeling with electrochemical and spectroscopic measurements. For this purpose, a model system composed of OmcA, a typical OM protein, and the hexagonal tungsten trioxide (h-WO ) with good biocompatibility is selected. The interfacial electron transfer is dependent mainly on the special molecular configuration of OmcA and the microenvironment of the solvent exposed active center. Also, the apparent electron transfer rate can be tuned by site-directed mutagenesis at the axial ligand of the active center. Furthermore, the equilibrium state of the OmcA/h-WO systems suggests that their attachment is attributed to the limited number of residues. The electrochemical analysis of OmcA and its variants reveals that the wild type exhibits the fastest electron transfer rate, and the transient absorption spectroscopy further shows that the axial histidine plays an important role in the interfacial electron transfer process. This study provides a useful approach to promote the site-directed mutagenesis and nanomaterial design for bioelectrocatalytic applications.
电活性微生物细胞已经进化出独特的细胞外电子转移机制，通过氧化还原外层膜（OM）蛋白来进行反应。然而，OM 蛋白和纳米材料界面处的电子转移机制仍不清楚。在这项研究中，通过将分子建模与电化学和光谱测量相结合，研究了生物/无机界面处的电子转移机制。为此，选择了由典型的 OM 蛋白 OmcA 和具有良好生物相容性的六方氧化钨（h-WO）组成的模型系统。界面电子转移主要取决于 OmcA 的特殊分子构型和暴露活性中心的溶剂微环境。此外，通过活性中心轴向配体的定点突变可以调节表观电子转移速率。此外，OmcA/h-WO 体系的平衡状态表明，它们的附着归因于有限数量的残基。对 OmcA 及其变体的电化学分析表明，野生型表现出最快的电子转移速率，瞬态吸收光谱进一步表明轴向组氨酸在界面电子转移过程中起着重要作用。这项研究为生物电催化应用中的定点突变和纳米材料设计提供了一种有用的方法。
