纤维素降解辅助蛋白及其作用机理研究进展

化石燃料的日渐枯竭及环境污染的日益严重使得生物质原料的资源化、能源化利用受到广泛关注。木质纤维素是地球上最丰富的可再生生物质，其通过生物转化可获得多种燃料和化学品，而纤维素难以有效糖化是木质纤维素生物转化的主要瓶颈。本文介绍了某些纤维素非降解性辅助蛋白提高纤维素酶解效率的相关研究进展，重点分析了近些年发现并研究较多的裂解性多糖单加氧酶（AA9和CBM33）、纤维二糖脱氢酶（CDH）、扩展蛋白（expansin）、膨胀素（SWOI）等几种纤维素辅助蛋白及其协助纤维素降解的机理，总结出这些辅助蛋白主要是通过促进木质素或半纤维素降解以及破坏纤维素的氢键网络和结构来协同纤维素酶催化纤维素的糖化降解。通过以上概括和评述，认为这些辅助蛋白虽然一定程度上可以促进纤维素的酶解，但其研究和应用还仅限于实验室基础研究，如何将其有效并廉价应用于木质纤维素生物转化的工业过程还面临着巨大挑战。指出相关研究工作的重点还需要从廉价而有效的蛋白筛选与构建、协同作用机理解析、过程优化与强化等方面深入开展。

Auxiliary proteins for boosting enzymatic hydrolysis of cellulose and the action mechanisms

Due to the depletion of fossil fuels and growing environmental pollution,more and more attention has been paid to the utilization of renewable biomass materials for production of fuels and chemicals. Lignocellulose is the most abundant renewable biomass on the earth,and it can be converted to various products by bioconversion process. However,the low efficiency of cellulose saccharification has become a bottle-neck for the lignocellulose bioconversion. In this review,the research progress on the improvement of enzymatic hydrolysis of cellulose by some non-hydrolytic auxiliary proteins has been introduced,especially focusing on the recent research work on several promising auxiliary proteins such as lytic polysaccharide monooxygenase(AA9 and CBM33),cellobiose dehydrogenase(CDH),expansins,swollenins(SWOI),and the corresponding action mechanisms to assist the cellulose biodegradation. It was generalized that these auxiliary proteins improved cellulose hydrolysis significanly by assisting the removal of hemicelluloses and lignin,and destroying cellulose hydrogen-bond network and structure thus enhancing cellulose accessibility to cellulases enzymes. It was concluded that auxiliary proteins may be promising to boost lignocellulose bioconversion; however,there are still many great challenges towards industrial applications of these proteins with low cost. Finally,it was pointed out that corresponding research work may include at least the screening and production of efficient but cheap auxiliary proteins,mechanism interpretation of the synergetic action between auxiliary protein and cellulases,and process optimization and intensification etc.