5-卤代尿嘧啶碱基与氨基酸光致交联反应机理的研究

The DNA/RNA containing 5-halouracils (5-XU) enhances the photosensitivity with respect to DNA/RNA–protein cross-linking. Generation of 5-halouracil-based photo-cross-linking is a widely used method for the investigation of interactions between proteins and DNA or RNA. It is thus essential to understand the molecular mechanisms of the photo-cross-linking between 5-XU and amino acids. In this work, we plan to perform time-resolved Fourier transform infrared spectroscopy (TR-FTIR) experiments in conjunction with UV-Vis transient absorption spectrum to investigate the photo-cross-linking mechanisms of the 5-bromouracil (5-BrU) and 5-iodoouracil (5-IU) with different amino acids, including aromatic and non-aromatic amino acids. Our result will present directly the experimental evidence to reveal the reaction mechanism by detecting the key transient intermediates and analyzing their kinetics. Furthermore, we will deeply study the effects of different halogen substituents, amino acids and excitation wavelengths on the mechanism of this photo-cross-linking reaction and extend the study from single amino acid molecule to polypeptide. These results will clearly provide the molecular reaction mechanism between 5-IU/5-BrU and various amino acids, which can provide a comprehensive and reliable reference for the photo-cross-linking mechanism of 5-XU substituted DNA/RNA with proteins.

5-卤代尿嘧啶（5-XU）生色团可使DNA/RNA的光敏感性增强，在紫外光作用下容易与蛋白质发生交联反应，广泛应用于研究核酸与蛋白质的相互作用。深入研究5-XU与氨基酸的光致交联反应机理可为发展5-XU取代的DNA/RNA与蛋白质的光致交联技术提供基础，有助于该技术在核酸与蛋白质相互作用研究领域的应用。本项目拟主要利用纳秒时间分辨傅立叶变换红外光谱（TR-FTIR）技术，结合纳秒紫外-可见瞬态吸收光谱研究5-碘代尿嘧啶（5-IU）和5-溴代尿嘧啶（5-BrU）与芳香氨基酸以及非芳香族氨基酸乃至多肽的光致交联反应机理，通过探测关键瞬态中间体，直接给出揭示反应机理的实验证据，深入探讨不同卤素取代基、氨基酸及激发波长对光致交联反应机制的影响。本研究有望清晰给出5-IU/5-BrU与各种氨基酸交联的分子反应机制，加深对DNA/RNA与蛋白质的光致交联反应机理的认识。

核酸与蛋白质的相互作用是生物体进行生命活动的基础, 光活化核苷酸引发的其与氨基酸共价交联反应是研究二者相互作用的有效手段。5-卤代尿嘧啶（5-XU）是一种被广泛应用于研究核酸与蛋白质的相互作用的取代碱基。深入研究5-XU与氨基酸的光致交联反应机理可为5-XU取代的DNA/RNA与蛋白质的光致交联技术提供基础，有助于该技术在核酸和蛋白质相互作用研究领域的应用。本项目主要利用纳秒时间分辨傅立叶变换红外光谱（TR-FTIR）技术，结合纳秒紫外-可见瞬态吸收光谱和理论计算方法确定了能够与5-溴代尿嘧啶（5-BrU）和5-碘代尿嘧啶（5-IU）发生光致交联反应的非芳香氨基酸及其作用位点，并澄清了光致交联反应机制。同时设计合成了5-溴代-4-硫代尿苷（5-Br-4-TUrd）双取代碱基，增大紫外吸收波长和光致交联产率，成功在瞬态光谱上探测到了光致交联反应中间体，从而揭示了其电子转移质子耦合反应机制。此外通过分析Au/TiO2的光电子动力学信息为该光催化剂的潜在应用提供了理论基础。在本项目的支持下，发表sci论文1篇（已标注），已整理结果待发表文章1篇，正在整理研究结果1篇。