Structure of rice-straw arabinoglucuronoxylan and specificity of Streptomyces xylanase toward the xylan.

Rice-straw treated with 5% ammonia water was hydrolyzed with the β-xylanase of Streptomyces sp. E-86, and four kinds of hetero-oligosaccharides, two arabinoxylo- and two glucuronoxylooligosaccharides, were isolated from the hydrolysate by charcoal column, gel filtration, ion-exchange, and aminopropyl silica column chromatographies. The structures of the oligosaccharides were identified as 32-α-l-arabinofuranosyl-xylobiose, 32-α-l-arabinofuranosylxylotriose, 23-4-O-methyl-α-d-glucuronosylxylotriose, and 23-α-d-glucuronosylxylotriose by the analysis of component sugar, partial acid hydrolysis, methylation analysis etc. Based on the structures of above oligosaccharides, the structure of rice-straw arabinoglucuronoxylan and the specificity of the xylanase toward the xylan are discussed.