天然结晶纤维素的生物合成及其去晶化途径  

Biosynthesis of Natural Crystal Cellulose and Its Decrystallization

作　　者：陈玉[1] 张怀强[1] 赵越[1] 高培基[1] 王禄山[1] 

机构地区：[1]山东大学微生物技术国家重点实验室,济南250100

出　　处：《生物化学与生物物理进展》2016年第8期747-757,共11页Progress In Biochemistry and Biophysics

基　　金：国家自然科学基金(31370111);国家科技重大专项(2013ZX10004217);山东大学基本科研业务费资助项目自然科学专项(2015YQ004)资助项目~~

摘　　要：纤维素是高等植物细胞壁的结构骨架和重要组成成分,由细胞质膜上的纤维素合成酶合成.一个纤维素合成酶亚基合成一根纤维素分子链,多个亚基聚集在一起形成末端复合体(TC),可同时合成多根葡聚糖分子糖链,其在氢键和范德华力作用下快速有序堆积,形成结构紧密的天然微纤丝结晶结构.质膜上有序线性排列的超分子TC合成结晶纤维素Ⅰα,而玫瑰花型排列的TC合成结晶纤维素Ⅰβ.结晶微纤丝的密切有效堆积是植物抗降解的天然屏障.高浓度的酸和离子液体可以在微纤丝间有效扩散,破坏晶体分子链的有序堆积、分子间氢键网络,甚至打断晶体内部的糖苷键,完成天然结晶纤维素的去晶化及解聚过程.酶分子的去晶化过程是发生在微纤丝特定表面上的非均相反应过程,可在常温常压下固或液表面上快速完成,但有效可及表面积是其主要限速瓶颈.因此结合物理、化学方法预处理,低成本高效打破限制酶分子有效扩散的屏障,增加酶分子对结晶纤维素特异性结合的效率和有效可及面积,从而实现天然结晶纤维素高效去晶化及绿色快速降解转化.Crystal cellulose that biosynthesized by the cellulose synthetase（Ces A）,is the structural framework and the most important components of the cell wall of higher plants.During the process of biological evolution,Ces A aggregates on the plasma membrane and forms super-molecular terminal complexes（TCs） which have the two types of arrangement： TCs and rosettes TCs,synthesizing Ⅰα and Ⅰβ crystal cellulose,respectively.Due to the unbranched structure,the adjacent cellulose chains can quickly stack side by side to form microfibre under the hydrogen bonds and Van der Waals＇ force（VDW）.As a result,tightly crystal super-molecular structure of microfibre work as a natural barrier and makes it become an obstacle to the degradation which is known as biomass recalcitrance.However,concentrated acids and ionic liquids can diffuse among the microfibre efficiently and break β-1,4-glucosidic bonds and hydrogen bonds,and eventually destroy the crystal structure of cellulose.Crystal cellulose can also be degraded by biological enzymes,which is quite different from chemical treatments which both require extremely acting conditions.Cellulases can hydrolysis crystal cellulose at room temperature,but only the certain surface of microfibre can be interacted with celluases,so the accessibility of cellulose surface further reduce the efficiency of hydrolysis.Therefore,the combination of physical and chemical pretreatments can break the biomass recalcitrance and then cellulases can spread into microfibre which resulting in the specific binding rates of enzyme-substrate increased.Finally,it can realize the degradation and conversion of natural crystal cellulose with low-cost and green high-efficiency.

关 键 词：纤维素合成酶复合体 生物质抗降解屏障 结晶纤维素 去晶化 绿色化工 

分 类 号：Q633[生物学—生物物理学]