Characterization of substituents in xylans from corn cobs and stover

Structural knowledge on hemicellulose from corn cobs and stover is helpful to better understand their position within the plant cell wall architecture as well as their enzymatic saccharification. In this research different extracts were prepared with water, 1 M and 4 M alkali. Most of the xylans were yielded in the 1 M alkali fractions. The xylans were substituted with arabinose and glucuronic acid; 9 and 5 (cobs) and 14 and 9 (stover) per 100 xylosyl residues, respectively. Also esterlinked groups were present, like acetic, ferulic and coumaric acids; 49, 4 and 6 (cobs) and 39, 2 and 5 per 100 xylosyl residues (stover), respectively. Incubation with a well-characterized endoxylanase showed a more blockwise distribution of side-groups for stover xylans compared to cobs. Analysis of soluble fractions of dilute acid treated cobs and stover showed that especially feruloylated oligomers were resistant.