Dissecting the Ultrafast Stepwise Bidirectional Proton Relay in a Blue-Light Photoreceptor
Dissecting the Ultrafast Stepwise Bidirectional Proton Relay in a Blue-Light Photoreceptor
复制标题
DOI：
10.1021/jacs.2c10206
复制
发表时间：
2023-02-15
影响因子：
15
通讯作者：
Zhong, Dongping
中科院分区：
文献类型：
--
作者：
Chen, Zijing;Kang, Xiu-Wen;Zhong, Dongping
通过氢键网络的质子中继对于实现蛋白质机器的功能至关重要，例如光合作用和光感受器。在质子传递过程中，剖析各个质子转移步骤的速率和能量学一直是一个挑战。在这里，我们设计了一个质子摇摆蓝光使用黄素（BLUF）域与黄素单核苷酸（FMN）-谷氨酸（E）-色氨酸（W）三联体，并解决了四个单独的质子转移步骤动力学使用超快光谱。我们发现，在形成FMN中心点-/E-COOH/ WH中心点+的光致电荷分离之后，质子首先从桥接E-COOH快速地跳跃到FMN-（TfPT 2 = 3.8ps; KIE = 1.0），随后是从WH中心点+到E-COO-的第二次质子转移。（TfPT 1 = 336 ps; KIE = 2.6），其立即摇回到W中心点（TrPT 1 = 85 ps; KIE = 6.7），随后质子从FMNH中心点返回到E-COO。（TrPT 2 = 34 ps; KIE = 3.3），最终电荷在FMN中心点-和WH中心点+之间复合以关闭反应循环。我们的研究结果使用BLUF结构域作为范例蛋白质在超快时间尺度上重新审视了Grotthuss机制。
Proton relays through H-bond networks are essential in realizing the functionality of protein machines such as in photosynthesis and photoreceptors. It has been challenging to dissect the rates and energetics of individual proton-transfer steps during the proton relay. Here, we have designed a proton rocking blue light using a flavin (BLUF) domain with the flavin mononucleotide (FMN)-glutamic acid (E)-tryptophan (W) triad and have resolved the four individual proton-transfer steps kinetically using ultrafast spectroscopy. We have found that after the photo-induced charge separation forming FMN center dot-/E-COOH/ WH center dot+, the proton first rapidly jumps from the bridging E-COOH to FMN- (TfPT2 = 3.8 ps; KIE = 1.0), followed by a second proton transfer from WH center dot+ to E-COO- (TfPT1 = 336 ps; KIE = 2.6) which immediately rocks back to W center dot(TrPT1 = 85 ps; KIE = 6.7), followed by a proton return from FMNH center dot to E-COO- (TrPT2 = 34 ps; KIE = 3.3) with the final charge recombination between FMN center dot- and WH center dot+ to close the reaction cycle. Our results revisited the Grotthuss mechanism on the ultrafast timescale using the BLUF domain as a paradigm protein.