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Excited-State Charge Transfer, Proton Transfer, and Exciplex Formation Revealed by Ultrafast Time-Resolved Spectroscopy in Human Telomeric Ribonucleic Acid Quadruplex
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2023-05-26 , DOI: 10.1021/acs.jpclett.3c00806
Chensheng Ma 1 , Joshua Chiu-Lok Chow 2 , Allen Ka-Wa Wong 2 , Qingwu Xiong 2 , Jacob Chomchoei 2 , Wai-Ming Kwok 2
Affiliation  

Guanine quadruplexes (GQs), important for genome stability and biotechnology application, can form from both DNA and RNA. However, unlike the study of DNA GQs, little research has been conducted on excited states of GQs from RNA, which due to the ribose 2′-hydroxy group have structures distinct from their DNA counterparts. Combining ultrafast broadband time-resolved fluorescence and transient absorption measurements, we report the first direct probe of excitation dynamics for a bimolecular GQ from human telomeric repeat-containing RNA taking the typical highly compacted parallel folding with a propeller-like loop structure. The result revealed a multichannel decay containing an unusual high-energy excimer featuring charge transfer deactivated by rapid proton transfer in the tetrad core region. It also identified an unprecedented exciplex displaying massively red-shifted fluorescence produced from charge transfer in the loop region. The findings underscore the role of structural conformation and base content in determining the energy, electronic attribution, and decay dynamics of GQ excited states.

中文翻译:

超快时间分辨光谱揭示人端粒核糖核酸四链体中的激发态电荷转移、质子转移和激基复合物形成

鸟嘌呤四联体 (GQ) 对基因组稳定性和生物技术应用很重要,它可以由 DNA 和 RNA 形成。然而,与 DNA GQ 的研究不同,很少有人对来自 RNA 的 GQ 的激发态进行研究,这是由于核糖 2'-羟基具有不同于其 DNA 对应物的结构。结合超快宽带时间分辨荧光和瞬态吸收测量,我们报告了第一个直接探测双分子 GQ 的激发动力学,来自人类端粒重复序列的 RNA 采用典型的高度紧凑的平行折叠和螺旋桨状环结构。结果显示多通道衰变包含一种不寻常的高能准分子,其特点是四分体核心区域的快速质子转移使电荷转移失活。它还发现了一个前所未有的激基复合物,该激基复合物显示出由环区电荷转移产生的大量红移荧光。这些发现强调了结构构象和碱基含量在确定 GQ 激发态的能量、电子归属和衰变动力学方面的作用。
更新日期:2023-05-26
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