芳香羧酸脱羧酶催化C-H键活化及二氧化碳固定化的研究

项目名称： 芳香羧酸脱羧酶催化C-H键活化及二氧化碳固定化的研究

项目编号： No.21472232

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 朱敦明

作者单位： 中国科学院天津工业生物技术研究所

项目金额： 91万元

中文摘要： 芳香烃的C-H键活化生成官能化合物是有机合成化学的重大挑战之一，工业废气CO2的固定合成有价值的有机化合物对于绿色生产至关重要。芳香羧酸脱羧酶（羧化酶）催化可逆的芳香羧酸脱羧反应和芳香烃的羧基化反应，然而已知的芳香羧酸脱羧酶的平衡都严重倾向于脱羧反应方向，不利于芳香烃羧基化，合成有价值的芳香羧酸类化合物。本项目将采用基因克隆或基因合成的手段获得不同来源的芳香羧酸脱羧酶，研究苯环上具有不同取代基的底物与它们催化可逆反应的热力学平衡之间的相互关系，培养得到这些脱羧酶的晶体并解析其分子结构，或者建立合适的模拟结构，从分子水平研究芳香羧酸脱羧酶（羧化酶）与底物的相互作用机制和催化反应机理，了解该类酶中影响其催化反应平衡的关键氨基酸位点和结构因素，在此基础上对芳香羧酸脱羧酶进行设计改造，获得能够高效催化芳香烃C-H键与CO2反应生成有机酸的酶催化剂，实现芳香烃C-H键活化及CO2固定。

中文关键词： 生物催化；生物合成；催化机制；生物转化；化学生物学

英文摘要： Aromatic C-H activation is one of the great challenges in synthetic organic chemistry.Fixation of carbon dioxide is very important because it convert the waste to valuable chemicals and reduce its greenhouse effect.Aromatic carboxylic acid decarboxylases catalyze the reversible decarboxylation of the carboxylic acids and the carboxylation of aromatics. However, in all cases, the equilibrium heavily favours the decarboxylation,which could not be applied in the synthesis of valuable aromatic carboxylic acids from aromatics and carbon dioxide.In this project, aromatic carboxylic acid decarboxylase genes of different origins will be obtained by genome mining, cloned and expressed in E. coli. The recombinant enzymes will be purified and biochemically characterized. They will be tested with a series of substrates with diverse structural features to explore the relationship between the substrate and the thermodynamic equilibrium of the reaction. Crystallization of these enzymes will be investigated to obtain the crystals and study their structures, in an effort to understand the substrate binding and catalytic mechanism of the enzymatic reactions, thus to identify the key amino acid residues and structural features which greatly affect the thermodynamic equilibrium of the reversible decarboxylation and carboxylation. Based on these knowledges and understanding, an aromatic carboxylic acid decarboxylase will be selected for further rational engineering to afford enzymes, which catalyze efficient C-H activation of aromatics and fixation of carbon dioxide to synthesize aromatic carboxylic acids of high value.

英文关键词： biocatalysis;biosynthesis;catalytic mechanism;biotransformation;chemical biology