Branched arabino-oligosaccharides isolated from sugar beet arabinan

Abstract

Sugar beet arabinan consists of an α-(1,5)-linked backbone of l-arabinosyl residues, which can be either single or double substituted with α-(1,2)- and/or α-(1,3)-linked l-arabinosyl residues. Neutral branched arabino-oligosaccharides were isolated from sugar beet arabinan by enzymatic degradation with mixtures of pure and well-defined arabinohydrolases from Chrysosporium lucknowense followed by fractionation based on size and analysis by MALDI-TOF MS and HPAEC. Using NMR analysis, two main series of branched arabino-oligosaccharides have been identified, both having an α-(1,5)-linked backbone of l-arabinosyl residues. One series carries single substituted α-(1,3)-linked l-arabinosyl residues at the backbone, whereas the other series consists of a double substituted α-(1,2,3,5)-linked arabinan structure within the molecule. The structures of eight such branched arabino-oligosaccharides were established.