Abstract: It is becoming increasingly important to get bioenergy from biomass with enzyme immobilization technology. The interactions between enzymes and carrier surfaces strongly influence the orientation of the immobilized enzymes and thereby affect catalytic efficiency. In this work, Parallel Tempering Monte Carlo (PTMC) simulations were performed to study the adsorption orientations of three kinds of bioenergy-related enzymes (lipase, cellobiohydrolase and hydrogenase) on different electrically charged surfaces and under different solution ionic strength conditions. Simulation results showed that the adsorption of the three enzymes was dominated by electrostatic interactions, and largely relied on the distribution of charged surface amino acids and the screening effect from ions in the solution. It was also found that lipase and hydrogenase adsorbed on negatively charged surface with the active sites toward the solution and the electron transfer channel close to the surface, respectively; while cellobiohydrolase took a preferred orientation on the positively charged surface. This work will provide some guidance for immobilization of industrial enzymes on carrier materials with proper orientation.

Key words: molecular simulation, enzyme immobilization, adsorption orientation, bioenergy, protein adsorption

摘要： 利用酶固定化技术来对生物质发酵获取生物能源已显得日益重要。酶与表面间的相互作用强烈影响固定化酶的取向，进而影响催化效率。本文采用并行退火蒙特卡洛（PTMC）方法对三种生物能源用酶（脂肪酶、纤维素酶和氢化酶）在不同的带电表面和离子强度下的吸附取向进行了模拟研究。模拟结果发现三种酶的吸附主要由静电吸引力主导，并且很大程度上与蛋白表面带电氨基酸的分布和溶液离子的静电屏蔽有关。脂肪酶和氢化酶在带负电表面上吸附，其活性位和电子转移通道分别为朝向溶液和靠近表面，而纤维素酶则在带正电表面上取得较优的吸附取向。本文研究结果可为工业用酶以合理的取向在载体材料表面固定化提供一定的指导。

关键词: 分子模拟, 酶固定化, 吸附取向, 生物能源, 蛋白质吸附