天津大学张发光团队报道了工程细胞色素P450催化联芳基偶联反应实现的氟化霉素的化学酶合成。相关研究成果于2024年7月10日发表于国际顶尖学术期刊《美国化学会杂志》。

将氟原子安装在天然产物上，有望产生具有改进或新颖药理特性的氟化分子。酶促氧化碳-碳偶联反应是合成联芳基结构的一种简单策略，但探索这种生产天然产物氟取代衍生物的方法仍然难以捉摸。

该文中，研究人员报告了结核分枝杆菌细胞色素P450（MtCYP₁₂₁）的蛋白质工程，用于构建一系列新的天然氟取代的霉环素衍生物。该方案利用了一种“混合”化学酶程序，该程序由酪氨酸苯酚裂解酶催化的从市售氟酚制备氟酪氨酸、分子间化学缩合得到环二酪氨酸，以及工程化的MtCYP₁₂₁催化的分子内联苯酚偶联反应来完成应变的大环结构组成。计算机理研究表明，MtCYP₁₂₁利用Cpd I从底物的近端酚羟基中提取一个氢原子来触发反应。

然后，构象变化使两个酚羟基足够接近，在口袋水分子的帮助下进行分子内氢原子转移。最终的双自由基偶联过程完成了分子内C-C键的形成。研究发现联芳基偶联反应的效率受到各种氟取代的影响，主要是由于存在不同的结合构象。

附：英文原文

Title: Chemoenzymatic Synthesis of Fluorinated Mycocyclosin Enabled by the Engineered Cytochrome P450-Catalyzed Biaryl Coupling Reaction

Author: Shuo-Han Li, Xue Zhang, Ze-Long Mei, Yongjun Liu, Jun-An Ma, Fa-Guang Zhang

Issue&Volume: July 10, 2024

Abstract: Installing fluorine atoms onto natural products holds great promise for the generation of fluorinated molecules with improved or novel pharmacological properties. The enzymatic oxidative carbon–carbon coupling reaction represents a straightforward strategy for synthesizing biaryl architectures, but the exploration of this method for producing fluorine-substituted derivatives of natural products remains elusive. Here, in this study, we report the protein engineering of cytochrome P450 from Mycobacterium tuberculosis (MtCYP121) for the construction of a series of new-to-nature fluorine-substituted Mycocyclosin derivatives. This protocol takes advantage of a “hybrid” chemoenzymatic procedure consisting of tyrosine phenol lyase-catalyzed fluorotyrosine preparation from commercially available fluorophenols, intermolecular chemical condensation to give cyclodityrosines, and an engineered MtCYP121-catalyzed intramolecular biphenol coupling reaction to complete the strained macrocyclic structure. Computational mechanistic studies reveal that MtCYP121 employs Cpd I to abstract a hydrogen atom from the proximal phenolic hydroxyl group of the substrate to trigger the reaction. Then, conformational change makes the two phenolic hydroxyl groups close enough to undergo intramolecular hydrogen atom transfer with the assistance of a pocket water molecule. The final diradical coupling process completes the intramolecular C–C bond formation. The efficiency of the biaryl coupling reaction was found to be influenced by various fluorine substitutions, primarily due to the presence of distinct binding conformations.

DOI: 10.1021/jacs.4c03499

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c03499