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Xylo-oligosaccharides Inhibit Enzymatic Hydrolysis by Influencing Enzymatic Activity of Cellulase from Penicillium oxalicum

Wang, Can, Lu, Xianqin, Gao, Jia, Li, Xuezhi, Zhao, Jian
Energy & fuels 2018 v.32 no.9 pp. 9427-9437
Penicillium oxalicum, beta-glucosidase, cellulose, computer simulation, endo-1,4-beta-glucanase, enzymatic hydrolysis, enzyme activity, hemicellulose, hydrolysates, hydrolysis, lignocellulose, thin layer chromatography, xylooligosaccharides
Xylo-oligosaccharides, as the important intermediates of hemicellulose degradation, widely exist in hydrolysate from pretreatment and enzymatic hydrolysis of lignocellulose. This study showed that xylo-oligosaccharides largely reduced the efficiency of cellulose hydrolysis, but this inhibition cannot be effectively relieved by increasing loading of cellulose substrate or cellulase. Xylo-oligosaccharides largely suppressed enzymatic activities of cellobiohydrolases, endoglucanases, and β-glucosidase of cellulase complexes, especially cellobiohydrolases, and adding cellobiohydrolases or suitable β-glucosidase to hydrolysis systems could increase cellulose conversion. Thin-layer chromatography assay indicated that xylotetraose was quickly degraded in the initial hydrolysis stage while xylotriose was still held a higher concentration until 24 h of hydrolysis, and it is speculated that xylotriose was a stubborn inhibitor of enzymatic hydrolysis. The molecular docking analysis showed that xylotriose preferred to combine in the tunnel of cellobiohydrolases, which was generally recognized as the substrate-binding site on cellobiohydrolases, and thus reduced the effectiveness of cellobiohydrolases.