Glycosidic bond rearrangements in isomeric xylobioses by yeast xylan‐degrading enzymes

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Abstract
The cells of Cryptococcus albidus induced for xylan‐degrading enzymes are capable of transforming 1,2‐β‐xylobiose and 1,3‐β‐xylobiose into 1,4‐β‐xylobiose, the natural inducer. The conversion involves transglyco‐sylation and hydrolysis catalyzed by β‐xylosidase and β‐xylanase. A probable intermediate of the conversion of 1,2‐β‐xylobiose was isolated and identified as a trisaccharide, 4‐O‐β‐xylopyranosyl‐2‐O‐β‐xylopyranosyl‐D‐xylopyranose. The trisaccharide is cleaved by purified endo‐1,4‐β‐xylanase of C. albidus mainly at the 1,2‐β‐linkage yielding xylose and 1,4‐β‐xylobiose.