陕西师范大学王长号团队报道了高效含银(I)基序DNA杂化催化剂用于对映选择性Diels–Alder反应。相关研究成果于2024年6月11日发表于国际一流学术期刊《德国应用化学》。

DNA固有的手性结构可作为构建DNA杂化催化剂的有吸引力的支架，用于有价值的对映选择性转化。基于双链和G-四链DNA的对映选择性催化已经取得了巨大进展，但DNA杂化催化剂的新设计策略要求很高，活性中心的原子分析仍然具有挑战性。DNA i基序结构可以通过不同的胞嘧啶-胞嘧啶碱基对进行微调，为设计DNA催化剂提供了一个新的平台。

该文中，研究人员发现含有与Cu（II）离子相互作用的胞嘧啶银（i）-胞嘧啶（C-Ag⁺-C）碱基对的，人类端粒i基序DNA（i基序脱氧核糖核酸（Ag⁺）/Cu²⁺）可以催化Diels-Alder反应，具有完全转化率和高达95%的对映体过量。如通过各种物理化学技术所表征的，Ag⁺的存在被证明可以取代半质子化胞嘧啶-胞嘧啶（C:C+）碱基对中的质子，并稳定DNA i基序以接受Cu（II）离子。

与DNA和Cu²⁺相比，i-基序DNA（Ag⁺）/Cu²⁺催化剂显示出约8倍的速率加速。基于DNA突变实验、热力学研究和密度函数理论计算，Cu（II）离子的催化中心通过分别与一个未配对腺嘌呤的一个氮7原子，和附近脱氧胸苷一磷酸和脱氧腺苷一磷酸的两个磷酸氧原子结合而位于特定的环区。

附：英文原文

Title: Efficient Silver(I)-Containing i-Motif DNA Hybrid Catalyst for Enantioselective Diels–Alder Reactions

Author: Xingchen Dong, Ziyang Qiu, Zixiao Wang, Jiaqi Li, Weijun Qin, Jingshuang Dang, Wenqin Zhou, Guoqing Jia, Yashao Chen, Changhao Wang

Issue&Volume: 11 June 2024

Abstract: The inherent chiral structures of DNA serve as attractive scaffolds to construct DNA hybrid catalysts for valuable enantioselective transformations. Duplex and G-quadruplex DNA-based enantioselective catalysis has made great progress, yet novel design strategies of DNA hybrid catalysts are highly demanding and atomistic analysis of active centers is still challenging. DNA i-motif structures could be finely tuned by different cytosine-cytosine base pairs, providing a new platform to design DNA catalysts. Herein, we found that a human telomeric i-motif DNA containing cytosine-silver(I)-cytosine (C-Ag+-C) base pairs interacting with Cu(II) ions (i-motif DNA(Ag+)/Cu2+) could catalyze Diels-Alder reactions with full conversions and up to 95% enantiomeric excess. As characterized by various physicochemical techniques, the presence of Ag+ is proved to replace the protons in hemiprotonated cytosine-cytosine (C:C+) base pairs and stabilize the DNA i-motif to allow the acceptance of Cu(II) ions. The i-motif DNA(Ag+)/Cu2+ catalyst shows about 8-fold rate acceleration compared with DNA and Cu2+. Based on DNA mutation experiments, thermodynamic studies and density function theory calculations, the catalytic center of Cu(II) ion is proposed to be located in a specific loop region via binding to one nitrogen-7 atom of an unpaired adenine and two phosphate-oxygen atoms from nearby deoxythymidine monophosphate and deoxyadenosine monophosphate, respectively.

DOI: 10.1002/anie.202407838

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202407838