Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
Science. 2011 Sep 2;333(6047):1279-82. doi: 10.1126/science.1208386.
A deeper mechanistic understanding of the saccharification of cellulosic biomass could enhance the efficiency of biofuels development. We report here the real-time visualization of crystalline cellulose degradation by individual cellulase enzymes through use of an advanced version of high-speed atomic force microscopy. Trichoderma reesei cellobiohydrolase I (TrCel7A) molecules were observed to slide unidirectionally along the crystalline cellulose surface but at one point exhibited collective halting analogous to a traffic jam. Changing the crystalline polymorphic form of cellulose by means of an ammonia treatment increased the apparent number of accessible lanes on the crystalline surface and consequently the number of moving cellulase molecules. Treatment of this bulky crystalline cellulose simultaneously or separately with T. reesei cellobiohydrolase II (TrCel6A) resulted in a remarkable increase in the proportion of mobile enzyme molecules on the surface. Cellulose was completely degraded by the synergistic action between the two enzymes.
对纤维素生物质糖化的更深入的机制理解可以提高生物燃料开发的效率。我们在这里通过使用高速原子力显微镜的一个高级版本，实时观察到单个纤维素酶对结晶纤维素的降解。观察到里氏木霉纤维二糖水解酶 I（TrCel7A）分子沿结晶纤维素表面单向滑动，但在某一点表现出类似于交通堵塞的集体停止。通过氨处理改变纤维素的结晶多晶形式，增加了结晶表面上可及车道的表观数量，从而增加了移动纤维素酶分子的数量。同时或分别用里氏木霉纤维二糖水解酶 II（TrCel6A）处理这种大体积结晶纤维素，导致表面上可移动酶分子的比例显著增加。两种酶的协同作用使纤维素完全降解。
