SEQUENCING OF XYLOGLUCAN OLIGOSACCHARIDES BY PARTIAL DRISELASE DIGESTION - THE PREPARATION AND QUANTITATIVE AND QUALITATIVE-ANALYSIS OF 2 NEW TETRASACCHARIDES

The pentasaccharide (XXG), [GRAPHICS] obtained from Rosa xyloglucan, w as converted to two isomeric tetrasaccharides, a and b (Xyl(1) . Glc(3 )), by mild acid hydrolysis. During hydrolysis in 2 M trifluoroacetic acid at 90 degrees C, optimal yields of a and b were obtained after 20 -40 min. Each tetrasaccharide was purified by preparative paper chroma tography and high-pressure liquid chromatography (HPLC). The two isome rs were distinguished by the products of their partial digestion with Driselase, which hydrolyses the glucosidic bonds sequentially from the non-reducing terminus: a and b yielded cellobiose and Xyl --> Glc --> Glc, respectively, showing that they were [GRAPHICS] respectively. Te trasaccharide b was chromatographically identical, upon HPLC on Dionex CarboPac PA1, with the tetrasaccharide produced from XXG by the actio n of Tropaeolum alpha-D-xylosidase, supporting the proposed structure. Xyloglucan oligosaccharides were assayed quantitatively by measuremen t of the yield of isoprimeverose (Xyl --> Glc) after complete Driselas e digestion.