Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States.
J Phys Chem B. 2024 Oct 24;128(42):10417-10426. doi: 10.1021/acs.jpcb.4c06186. Epub 2024 Oct 11.
Recent efforts have sought to develop paramagnetic molecular quantum bits (qubits) as a means to store and manipulate quantum information. Emerging structure-property relationships have shed light on electron spin decoherence mechanisms. While insights within molecular quantum information science have derived from synthetic systems, biomolecular platforms would allow for the study of decoherence phenomena in more complex chemical environments and further leverage molecular biology and protein engineering approaches. Here we have employed the exchange-coupled = 1/2 FeS active site of putidaredoxin, an electron transfer metalloprotein, as a platform for fundamental mechanistic studies of electron spin decoherence toward spin-based biological quantum sensing. At low temperatures, decoherence rates were anisotropic, reflecting a hyperfine-dominated decoherence mechanism, standing in contrast to the anisotropy of molecular systems observed previously. This mechanism provided a pathway for probing spatial effects on decoherence, such as protein vs solvent contributions. Furthermore, we demonstrated spatial sensitivity to single point mutations via site-directed mutagenesis and temporal sensitivity for monitoring solvent isotope exchange. Thus, this study demonstrates a step toward the design and construction of biomolecular quantum sensors.
最近的研究努力旨在开发顺磁分子量子位（qubit），作为存储和操纵量子信息的一种手段。新兴的结构-性质关系揭示了电子自旋退相干机制。虽然分子量子信息科学的研究进展源自合成系统，但生物分子平台将允许在更复杂的化学环境中研究退相干现象，并进一步利用分子生物学和蛋白质工程方法。在这里，我们采用了来自于变形菌血红素蛋白（putidaredoxin）的 = 1/2 FeS 活性位点作为平台，用于对基于电子自旋的生物量子传感中的电子自旋退相干进行基础性的机制研究。在低温下，退相干速率具有各向异性，反映了超精细主导的退相干机制，这与以前观察到的分子系统的各向异性形成了鲜明对比。这种机制为探测退相干的空间效应（如蛋白质与溶剂的贡献）提供了一种途径。此外，我们通过定点突变展示了对单点突变的空间敏感性，并通过监测溶剂同位素交换展示了对时间的敏感性。因此，这项研究朝着设计和构建生物分子量子传感器迈出了一步。
