| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1390164 | Carbohydrate Research | 2015 | 9 Pages |
•Structural characterization of abundant unhydrolyzed linkages of Switchgrass xylan.•LC-MSn analysis of xylan end-point digestion oligosaccharide products.•SG xylan structures limit α-arabinofuranosidase activity of commercial enzymes.•A GH 62 α-arabinofuranosidase hydrolyzes the most abundant oligosaccharide products.
Switchgrass (Panicum virgatum, L.) is a potential renewable source of carbohydrates for use in microbial conversion to biofuels. Xylan comprises approximately 30% of the switchgrass cell wall. To understand the limitations of commercial enzyme mixtures, alkali-extracted, isolated switchgrass xylan was hydrolyzed by the action of two commercial enzyme cocktails, in the presence and absence of an additional α-arabinofuranosidase enzyme. The two most abundant enzymatic digestion products from each commercial enzyme treatment were separated and characterized by LC-MSn, linkage analysis, and NMR. The most abundant oligosaccharide from each commercial cocktail was susceptible to hydrolysis when supplemented with a GH62 α-arabinofuranosidase enzyme; further characterization confirmed the presence of (1→3)-α-arabinose linkages. These results demonstrate the lack of the required selectivity for arabinose-containing substrates in the commercial enzyme preparations tested. One product from each condition remained intact and was found to contain (1→2)-β-xylose-(1→3)-α-arabinose side chains; this linkage acts as a source of oligosaccharide recalcitrance.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide
