聚酯水解酶PETase的机理和进化改造的理论研究

聚对苯二甲酸乙二醇酯（PET）的广泛使用引起了严重的环境问题，使用生物酶法降解PET为单体分子，再回收利用是处理PET废弃物最理想的方法。新近发现的一种聚酯水解酶PETase是迄今为止在温和条件下PET降解活性最高的酶，但其活性和热稳定性还需进一步提高以达到工业化的要求。本项目拟采用量子力学/分子力学动力学模拟(QM/MM-MD)方法在PETase催化水解PET的机理和PETase的进化改造方面展开一系列的理论研究工作。首先将结合神经网络算法提高QM/MM-MD的计算效率，在分子级别研究酶与PET的结合模式和反应机理。本项目还将发展酶活性设计方案，利用机器学习，建立突变与活性关系用于构建突变体库，筛选高活性、高稳定性的突变体，为实验提供可靠的理论依据，缩减实验的规模。本项目的研究成果和手段可进一步应用于水解其它芳香族聚酯，以补救塑料在自然界中积累的环境危害。

Widespread utilization of polyethylene terephthalate (PET) has caused serious environmental problems. It’s a promising solution to enzymatically degrade PET polymer into monomers and recycle it. Although the newly discovered polyester hydrolase enzyme, PETase, has the highest PET degradation activity under mild conditions of all PET-degrading enzymes reported to date, its activity and thermal stability need to be further improved to meet the requirements of industrialization. In this project, we’ll employ the quantum mechanics/molecular mechanics dynamics simulation (QM/MM-MD) method to carry out a series of theoretical research work on the mechanism of PET hydrolysis catalyzed by PETase and the evolution of PETase. Firstly, under the combination of the QM/MM-MD and neural network method, the binding mode of PET with PETase and reaction mechanism of hydrolysis will be studied on the molecular level. Furthermore, this project will develop an enzyme activity design strategy, build the mutant library through the relationship between mutation and activity using machine learning, and screen PETase mutants with high activity and thermal stability. Our project can provide a reliable theoretical basis for the experiment, and help to reduce the scale of it. Moreover, our research results and methods can be further applied to hydrolyze other aromatic polyesters to remedy their environmental hazards accumulated in nature.