UCST型响应性高分子的调控制备及其负载纤维素酶的构效与机制研究

纤维素的开发利用对于能源、经济与环境皆具有重要意义，而绿色的酶法纤维素转化技术已成为该领域的研究热点及发展趋势之一。在酶法中，将纤维素酶固定虽可稳定酶结构并实现其循环利用，但固定的酶与不溶性底物间所存在的传质障碍将致使纤维素水解效率较低。基于此，本项目提出了“液相水解促传质，固相回收稳酶构”的科学设想。根据甲基丙烯酸-丙烯酸共聚物与明胶分子间可形成多重氢键作用的原理，调控制备出具有高临界相转变温度（UCST）特征的响应性高分子。通过甲基丙烯酸-丙烯酸共聚物对纤维素酶分子的共价修饰以及明胶在聚乙烯膜表面的接枝调控，构建可逆固定酶体系，实现酶的液态高效催化与固态高效回收。本研究以纤维素高效转化需求为牵引，拟揭示共聚物结构与UCST间的构效关系；研究接枝聚合条件对明胶接枝密度的影响规律；阐明体系中影响酶释放回收效率的因素与机制。本项目从固液相变的角度突破传质瓶颈，具有很好的科学意义和应用价值。

Utilization of cellulose is of great significance to energy, economy and environment in which the green enzymatic cellulose conversion technology has become one of the research hotspots and the development trends. In the enzymatic method, immobilization of cellulase can stabilize its structure and realize its recycling. However, the mass transfer barrier between the immobilized cellulase and the insoluble cellulose always cause the cellulose hydrolysis in low efficiency. In this proposal, the applicant has proposed a scientific assumption, which cellulase can hydrolyze the cellulose in high efficiency in liquid phase while can be stabilized and recycled in solid phase. On the basis of that the multiple hydrogen bond can be generated between poly(methyl acrylic acid)/poly(acrylic acid) co-polymer and gelatin, a series of polymers with different upper critical solution temperature (UCST) will be prepared. By studying the covalent modification of cellulase with poly(methyl acrylic acid)/poly(acrylic acid) co-polymer and the grafting regulation of gelatin on polyethylene film, the reversible cellulase immobilization system will be constructed to realize the high catalytic efficiency and good operational stability of cellulase. In this proposal, based on the demand for high efficiency cellulose conversion, the structure-activity relationship and the influence rules of the co-polymer structure on the UCST of the modified cellulase will be revealed; the effect of reaction condition on the gelatin grafting density will be researched; and the influential factors and the mechanism of the releasing/recovering efficiency in the reversible cellulase immobilization system will be illustrated. The mass transfer barrier problem will be finally solved based on the liquid-solid phase transition. It is of great significance in both scientifically and industrially.