Preparation of β(1→6)-linked galactofuranoside oligomers from the acidic polysaccharide of Fusarium sp. M7-1

This paper describes a method of preparating β(1→6)-linked galactofuranoside oligomers. The main structure of the acidic polysaccharide of Fusarium sp. M7-1 has a linear chain composed of β(1→6)-linked galactofuranose residues. For preparation of the β(1→6) galactofuranoside oligomers, glucuronic acid residues were converted to unsaturated sugars using an acidic polysaccharide lyase from Cellulomonas sp. Mild acid hydrolysis was found to be very effective in preparing the β(1→6) galactofuranoside oligomers from the unsaturated polysaccharide of Fusarium sp. M7-1. After treatment with 1 M acetic acid at 100°C for 5 h, the unsaturated polysaccharide was separated into oligomers, and the primary structures of the β(1→6) galactofuranoside oligomers were resolved, mainly by 400-MHz ¹H-NMR spectrometry. These oligomers were resistant to commercial β-d-galactosidases.