胺转氨酶（amine transaminase）的立体选择性机制研究

Chiral amines are crucial building blocks in the synthesis of some pharmaceutical drugs, which has been widely used in agriculture and medicine industry and occupied an important position in the national economy and people's lives. Different configurations of chiral amines possess different pharmacological activities and thus to produce pure chiral amine has becoming increasingly important. Ab-R-ATA is an amine transaminase from Arthrobacter sp. and can produce (R)-enantiomers with enantiomeric excess (ee) value higher than 99% with excellent stereoselectivity, low cost and non-pollution to the environment. However, the mechanism of the strict stereoselectivity of Ab-R-ATA is unknown yet. This project aims at deep research of the stereoselective catalytic process by using biochemical and molecular biological analysis. In addition, this project also aims at illuminating the molecular mechanisms of the stereoselectivity of Ab-R-ATA by analyzing the crystal structure of the complex of Ab-R-ATA and its substrate, combining with site-directed mutagenesis and high performance liquid chromatography (HPLC). For the first time, this work will reveal mechanisms of the stereoselectivity of the amine transaminases. These results will probably provide theoretical basis for designing the novel chiral amine compounds and structural basis for the molecular modification of the amine transaminases.

手性胺类化合物是药物合成过程中重要的中间体，通过酶法制备单一构象的手性胺既是目前的研究热点也具有重要的研究价值。胺转氨酶Ab-R-ATA可以用来合成多种重要的手性胺化合物且产物对映体过量值（enantiomeric excess, ee）大于99%，但其特有的高立体选择性分子机制还不清楚。本项目以Ab-R-ATA为研究对象，首先以光谱学的实验方法对Ab-R-ATA的立体选择性催化过程进行深入的研究；然后摸索制备稳定的Ab-R-ATA与氨基供体化合物复合体的反应条件；此后通过蛋白质X射线结晶学的方法解析Ab-R-ATA与氨基供体化合物复合体的三维立体结构，并结合定点突变技术与高效液相色谱（HPLC）等试验方法系统阐明Ab-R-ATA底物立体选择性识别的分子机制。该研究将首次揭示胺转氨酶的立体选择性分子机制，为开发新型手性胺化合物提供重要的理论基础，同时将为胺转氨酶的分子改造提供结构依据。