Direct Observation of Ultrafast Proton Rocking in the BLUF Domain
Direct Observation of Ultrafast Proton Rocking in the BLUF Domain
复制标题
直接观察 BLUF 域中的超快质子摇摆
DOI：
10.1002/anie.202114423
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发表时间：
2022-01-20
影响因子：
16.6
通讯作者：
Zhong, Dongping
中科院分区：
文献类型：
--
作者：
Kang, Xiu-Wen;Chen, Zijing;Zhong, Dongping
我们直接观察到 BLUF 结构域蛋白支架中心基序中的超快质子摇摆。突变体设计考虑了通过用Trp取代原始基序中的Tyr来调节质子耦合电子转移（PCET）驱动力，以消除竞争性电子转移途径的干扰。使用飞秒泵浦探针光谱和详细的动力学分析，我们解决了沿着 FMN-Gln-Trp 质子中继链的电子转移耦合 Grotthuss 型正向和反向质子摇摆。正向和反向质子转移速率被确定为非常接近，即 51 ps 与 52 ps。与正向和反向质子转移相关的动力学同位素效应 (KIE) 常数分别为 3.9 和 5.3。超快质子摇摆的观察不仅是揭示BLUF结构域中质子传递本质的关键一步，而且为蛋白质中质子转移的理论研究提供了新的范式。
We present direct observation of ultrafast proton rocking in the central motif of a BLUF domain protein scaffold. The mutant design has taken consideration of modulating the proton-coupled electron transfer (PCET) driving forces by replacing Tyr in the original motif with Trp, in order to remove the interference of a competing electron transfer pathway. Using femtosecond pump-probe spectroscopy and detailed kinetics analysis, we resolved an electron-transfer-coupled Grotthuss-type forward and reverse proton rocking along the FMN-Gln-Trp proton relay chain. The rates of forward and reverse proton transfer are determined to be very close, namely 51 ps vs. 52 ps. The kinetic isotope effect (KIE) constants associated with the forward and reverse proton transfer are 3.9 and 5.3, respectively. The observation of ultrafast proton rocking is not only a crucial step towards revealing the nature of proton relay in the BLUF domain, but also provides a new paradigm of proton transfer in proteins for theoretical investigations.