Department of Biological and Agricultural Engineering, University of California at Davis, Davis, CA 95616, United States.
Carbohydr Polym. 2013 Sep 12;97(2):581-6. doi: 10.1016/j.carbpol.2013.05.027. Epub 2013 May 21.
There is a need to understand how cellulose structural properties impact productive cellulase-cellulose interactions toward solving the mechanisms of the heterogeneous reaction. We coupled biochemical studies of cellulose hydrolysis by a purified Trichoderma reesei Cel7A (TrCel7A) cellobiohydrolase with atomic force microscopy (AFM) to study the impact of the cellulolytic activity on the fibrillar structure of cellulose. Bacterial cellulose (BC) fibrils were hydrolyzed by TrCel7A then immobilized by hydrophobic interactions on glass for AFM imaging. Commonly used methods to culture and isolate cellulose fibrils resulted in significant oxidation of the reducing-ends but minimal oxidation along the fibrils. We observed extensive fibrillation of BC fibrils to ∼3 nm microfibrils during the course of hydrolysis by TrCel7A, leaving thinned un-fibrillated recalcitrant fibrils at >80% hydrolysis extents. Additionally, this remaining fraction appeared to be segmented along the fibril length.
需要了解纤维素结构特性如何影响生产性纤维素酶-纤维素相互作用，以解决非均相反应的机制。我们将纤维素水解的生化研究与原子力显微镜（AFM）相结合，研究了纤维素酶活性对纤维素纤维结构的影响。通过 Trichoderma reesei Cel7A（TrCel7A）纤维二糖水解酶将细菌纤维素（BC）纤维水解，然后通过疏水相互作用将其固定在玻璃上进行 AFM 成像。通常用于培养和分离纤维素纤维的方法会导致还原端发生明显的氧化，但沿纤维的氧化程度最小。我们观察到在 TrCel7A 的水解过程中，BC 纤维发生了广泛的纤维化，形成了约 3nm 的微纤维，而在水解程度达到>80%时，留下了变薄的未纤维化的抗性纤维。此外，该剩余部分似乎沿纤维长度分段。
