Gold(I) compounds are known to bind sulfur-containing proteins, forming the basis in the design of gold(I)-based drugs. However, the intrinsic molecular mechanism of the chemical reaction is easily hidden when monitored in ensemble. We have previously demonstrated that Mycobacterium smegmatis porin A (MspA) can be engineered (MspA-M) to contain a specialized nanoreactor to probe chemical reactions involving tetrachloroaurate(III). Here, we provide further investigations of coordination interactions between dichloroaurate(I) and MspA-M. Gold compounds of different coordination geometry and valence states are as well probed and evaluated, demonstrating the generality of MspA-M. With single-molecule evidence, MspA-M demonstrates a preference for dichloroaurate(I) than tetrachloroaurate(III), an observation in a single molecule that has never been reported. By counting the maximum number of simultaneous ion bindings, the narrowly confined pore restriction also efficiently distinguishes dichloroaurate(I) and tetrachloroaurate(III) according to their differences in geometry or size. The above demonstration complemented a previous study by demonstrating other possible gold-based single-molecule chemical reactions observable by MspA. These observations bring insights in the understanding of gold-based coordination chemistry in a nanoscale.

中文翻译：

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单分子双氯金酸酯（I）结合工程改造的耻垢分枝杆菌孔蛋白A（MspA）纳米孔的观察。

已知金（I）化合物可结合含硫蛋白质，从而构成了基于金（I）的药物设计的基础。但是，在整体监控时，化学反应的内在分子机制很容易被隐藏。我们之前已经证明了耻垢分枝杆菌可以设计孔蛋白A（MspA）（MspA-M），使其包含专门的纳米反应器，以探测涉及四氯金酸酯（III）的化学反应。在这里，我们提供进一步研究二氯金酸酯（I）和MspA-M之间的配位相互作用。还探查和评估了不同配位几何形状和化合价态的金化合物，证明了MspA-M的普遍性。有单分子证据，MspA-M证明比四氯金酸酯（III）更偏爱二氯金酸酯（I），这一发现从未报道过。通过计算同时离子结合的最大数量，狭窄的孔限制也可以根据它们在几何形状或大小上的差异有效地区分二氯金酸酯（I）和四氯金酸酯（III）。上面的演示通过展示MspA可以观察到的其他可能的金基单分子化学反应，对先前的研究进行了补充。这些观察为了解纳米级金基配位化学带来了见识。