University of Helsinki, Department of Physics, P.O. Box 64, FI-00014 Helsinki, Finland.
Bioresour Technol. 2013 Feb;129:135-41. doi: 10.1016/j.biortech.2012.11.017. Epub 2012 Nov 19.
The role of xylan as a limiting factor in the enzymatic hydrolysis of cellulose was studied by hydrolysing nanocellulose samples prepared by mechanical fibrillation of birch pulp with varying xylan content. Analyzing the nanocelluloses and their hydrolysis residues with dynamic FT-IR spectroscopy revealed that a certain fraction of xylan remained tightly attached to cellulose fibrils despite partial hydrolysis of xylan with xylanase prior to pulp fibrillation and that this fraction remained in the structure during the hydrolysis of nanocellulose with cellulase mixture as well. Thus, a loosely bound fraction of xylan was predicted to have been more likely removed by purified xylanase. The presence of loosely bound xylan seemed to limit the hydrolysis of crystalline cellulose, indicated by an increase in cellulose crystallinity and by preserved crystal width measured with wide-angle X-ray scattering. Removing loosely bound xylan led to a proportional hydrolysis of xylan and cellulose with the cellulase mixture.
通过用木聚糖酶对不同木聚糖含量的桦木浆进行机械打浆来制备纳米纤维素样品，研究了木聚糖作为纤维素酶水解过程中限制因素的作用。用动态傅里叶变换红外光谱法对纳米纤维素及其水解残渣进行分析，结果表明，尽管在打浆前用木聚糖酶对木聚糖进行了部分水解，但仍有一部分木聚糖紧密附着在纤维素纤维上，并且在纤维素酶混合物水解纳米纤维素的过程中，这部分木聚糖仍保持在结构中。因此，可以预测，有一部分松散结合的木聚糖可能更容易被纯化的木聚糖酶去除。通过广角 X 射线散射测量，发现存在松散结合的木聚糖会限制结晶纤维素的水解，结晶纤维素的结晶度增加，晶体宽度保持不变。用纤维素酶混合物去除松散结合的木聚糖会导致木聚糖和纤维素的比例水解。
