.BETA.-1,3-Xylanase and .BETA.-1,4-xylanase action on rhodymenan.

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Abstract
A purified extracellular endo β-1, 3-xylanase (EC 3.2.1.32) from an isolated strain, Aspergillus reus A-07, was found to hydrolyze 1, 3-xylosyl linkages only. When rhodymenan (β-1, 4 and β-1, 3-linked xylan) was hydrolyzed by β-1, 3-xylanase (EF-6), four β-1, 4-linked xylooligosaccharide ictions were produced. The main product was β-1, 4-xylotriose, with trace amounts of other β-1, 4-ked xylooligosaccharides. Successive degradation by β-1, 4-xylosidase of the β-1, 4-looligosaccharides that were produced from hydrolysis of β-1, 3-xylanase on rhodymenan yielded ly xylose as the final product. We compared the action pattern of this enzyme with that of an extracellular endo β-1, 4-lanase (EC 3.2.1.8) of Streptomyces. From a mixture of products of β-1, 4-xylanase hydrolysis on adymenan, an isomeric xylotriose was isolated by charcoal chromatography after treating with β-1, 4-xylosidase. The structure of this isomeric xylotriose was elucidated by methylation analysis and susceptibility to β-1, 4-xylanase, β-1, 3-xylanase, and β-1, 4-xylosidase. The obtained isomeric lotriose was identified as 3-O-β-xylopyranosyl-4-O-β-D-xylopyranosyl-D-xylose (XI→3X1→4X). It has a melting point of 224-225°C and [α]20D(c=1, H20)= -46°.

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