纤维素酶在木质素上的吸附规律和机制及弱木质素吸附性酶的构建

利用木质纤维素生物转化生产液体燃料和化学品是当前国际上研究的热点，其中将纤维底物用酶水解成可发酵糖是关键。已知木质素对酶的非生产性吸附影响纤维素的酶解效率，但已有木质素对酶吸附研究集中在木质素对纤维素酶液中蛋白量和酶活的影响以及对几个主要酶组分的吸附和机制研究，无法全面反映木质素对具有复杂酶系组成的纤维素酶的吸附规律及对纤维素酶解的影响机制。项目拟在全酶系水平上，系统研究木质素对不同来源的纤维素酶及其酶系中不同蛋白组分的吸附规律及对不同酶组分活性的影响机制，揭示多蛋白体系中不同蛋白在木质素吸附中的相互影响规律，从酶的结构和性质角度阐明木质素对不同酶组分吸附和对酶活性影响存在差异性的机制，在此基础上，通过构建“弱木质素吸附性和强纤维素吸附性”的酶组分和针对不同底物的高效降解酶系，实现低酶用量下纤维底物的高效水解。研究对后续通过理性设计改造纤维素酶和纤维素酶系、完善木质素对纤维素酶的吸附机制等具有重要意义。

Now, bioconversion of renewable lignocellulose for producing liquid flues and chemicals is a hot topic in the world, in which, a key step is that lignocellulose is hydrolyzed to fermentable sugar using cellulase. In the enzymatic hydrolysis of lignocellulose, however, the non-productive adsorption of enzymes onto lignin affects the enzymatic hydrolysis of cellulosic substrates. The studies about the adsorption of cellulase onto lignin from literatures were focused on the influence of lignin on free protein concentration in the enzyme solution and different enzymatic activity, and focused on studying the rule and mechanism of adsorption of limited several main components in cellulase such as Cellobiohydrolase(CBH), endoglucanase(EG) and β-glucosidase onto lignin. It is difficult to fully reveal the rule of adsorption of cellulase with a complex system onto lignin and mechanism of the effect of lignin adsorption on enzymatic hydrolysis using the results from literatures. . In this project, adsorption rules of different source cellulase and different components in crude cellulase liquor such as various enzyme components and non-enzymatic proteins onto lignin will be systematically studied at the level of the whole enzymatic system of cellulase rather than several main enzyme components, and and influence of the lignin adsorption on enzymatic activity of different enzyme components will be evaluated. The interactions of different protein during adsorption of enzymes to lignin will also be investigated in the multi protein system. The differences on adsorption of different enzyme components onto lignin and on effect of the adsorption on catalytic ability of different enzyme components will be compared and the differences mechanism will be elucidated from the protein structure and properties of different enzyme angle. Based on the results, the enzyme with the ability of weak-lignin-adsorption and strong-cellulose-adsorption will be constructed by enzymatic engineering modification, and the cellulase with high-efficiency degrading enzymatic system will be built according to the characteristics of different cellulosic substrates for achieving effective degradation of cellulosic substrates under low dosage of cellulase. The study is of great significance for modifying cellulase system by rational design method and more understanding the adsorption mechanism of enzyme onto lignin.