Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen , Rolighedsvej 23, DK-1958 Frederiksberg C, Denmark.
J Agric Food Chem. 2014 Apr 30;62(17):3800-5. doi: 10.1021/jf5012962. Epub 2014 Apr 22.
Biological degradation of biomass on an industrial scale culminates in high concentrations of end products. It is known that the accumulation of glucose and cellobiose, end products of hydrolysis, inhibit cellulases and decrease glucose yields. Aside from these end products, however, other monosaccharides such as mannose and galactose (stereoisomers of glucose) decrease glucose yields as well. NMR relaxometry measurements showed direct correlations between the initial T2 of the liquid phase in which hydrolysis takes place and the total glucose production during cellulose hydrolysis, indicating that low free water availability contributes to cellulase inhibition. Of the hydrolytic enzymes involved, those acting on the cellulose substrate, that is, exo- and endoglucanases, were the most inhibited. The β-glucosidases were shown to be less sensitive to high monosaccharide concentrations except glucose. Protein adsorption studies showed that this inhibition effect was most likely due to catalytic, and not binding, inhibition of the cellulases.
在工业规模上，生物质的生物降解最终会导致终产物浓度升高。众所周知，水解的终产物葡萄糖和纤维二糖会抑制纤维素酶并降低葡萄糖得率。然而，除了这些终产物之外，其他单糖（如葡萄糖的立体异构体甘露糖和半乳糖）也会降低葡萄糖的得率。NMR 弛豫测量表明，水解过程中液相的初始 T2 与纤维素水解过程中的总葡萄糖产量之间存在直接相关性，表明低游离水的可用性会导致纤维素酶抑制。在所涉及的水解酶中，作用于纤维素底物的酶，即外切和内切葡聚糖酶，受到的抑制最大。β-葡萄糖苷酶显示对高单糖浓度（除葡萄糖外）的敏感性较低。蛋白质吸附研究表明，这种抑制作用很可能是由于纤维素酶的催化而不是结合抑制。
