Mboowa Drake, Khatri Vinay, Saddler Jack N
Forest Products Biotechnology/Bioenergy Group, Faculty of Forestry, Department of Wood Science, University of British Columbia 2424 main mall Vancouver BC V6T 1Z4 Canada
RSC Adv. 2020 Jul 21;10(45):27152-27160. doi: 10.1039/d0ra05333c. eCollection 2020 Jul 15.
The influence of drying on cellulose accessibility and enzymatic hydrolysis was assessed. Dissolving pulp was differentially dried by freeze-, air- and oven-drying at 50 °C and subsequently hydrolyzed using the commercial CTec 3 cellulase preparation. It was apparent that drying reduced the ease of enzymatic hydrolysis of all of the substrates with a pronounced reduction (48%) exhibited by the oven-dried pulp. To assess if the ease of hydrolysis was due to enzyme accessibility to the substrate, microscopy (SEM), FTIR spectroscopy, water retention value (WRV), fiber aspect ratio analysis, Simons' stain and the selective binding of Fluorescent Protein-tagged Carbohydrate Binding Modules (FP-CBMs): CBM3a (crystalline cellulose) and CBM17 (amorphous cellulose) in combination with confocal laser scanning microscopy (CLSM) were used. The combined methods indicated that, if the gross characteristics of the substrate limited enzyme accessibility, the cellulases, as represented by the FP-CBMs, could not in turn access the finer structural components of the cellulosic substrates.
评估了干燥对纤维素可及性和酶水解的影响。溶解浆通过在50°C下冷冻干燥、空气干燥和烘箱干燥进行差异干燥，随后使用商业CTec 3纤维素酶制剂进行水解。很明显，干燥降低了所有底物的酶水解容易程度，烘箱干燥的纸浆表现出显著降低（48%）。为了评估水解容易程度是否归因于酶对底物的可及性，使用了显微镜（SEM）、傅里叶变换红外光谱（FTIR）、保水值（WRV）、纤维长径比分析、西蒙斯染色以及荧光蛋白标记的碳水化合物结合模块（FP-CBMs）：CBM3a（结晶纤维素）和CBM17（无定形纤维素）与共聚焦激光扫描显微镜（CLSM）结合的选择性结合。综合方法表明，如果底物的总体特征限制了酶的可及性，那么以FP-CBMs表示的纤维素酶就无法反过来接触纤维素底物的更精细结构成分。
