Aldotriouronic acids

Hamilton and N. S. Thompson, by fractionation of a partial hydroly-zate of a xylan on filter paper, isolated 4-0-methyl-D-glucuronic acid, the aldobiouronic acid mentioned above, and a crystalline aldotriouronic acid identified as 0-(4-0-methyl-a-D-glucopyranosyluronic acid)-(l —> 2)-0-/3-d-xylopyranosyl-(l 4)-D-xylopyranose. As the isomeric aldotriouronic acid was virtually absent, the authors suggested that, in the xylan polyuronide... 

Aldotriouronic acids, 73 Alginic acid, fractionation, 55 L-guluronic acid in, 88 Alkaloids, biosynthesis of, 269 Allose, 2-amino-2-deoxy-n-, derivatives of, 191... 

The hemicelluloses of wood contain uronic acid residues which frequently bear methyl ether groups. Hydrolysis of the hemicelluloses yields aldobioLironic and aldotriouronic acids. In researches referred to previously (page 300), O Dwyer " investigated the hemicelluloses from oakwood. She isolated an aldobiouronic acid as a barium salt after combined enzymic and acidic hydrolysis. Analyses of this compound were in agreement with the empirical formula for a barium salt of an 0-methyl-xylo-aldobiouronic acid. This compound was isolated from a polysaccharide material which contained xylose (6 parts), uronic acid (1 part), and methoxyl (1 part). Studies by Anderson on the hemicelluloses of a number of hardwoods also showed that 0-methylhexuronic acid residues are present in glycosidic union with xylose, in ratios extending from 8 to 19 xylose units per uronic acid unit. 

The stability toward acid hydrolysis of glycosiduronic linkages was referred to earlier. 2-0-(4-0-Methyl-a-n-glucopyranosyluronic acid)-n-xylopyranose (1) is hydrolyzed twenty times slower than 2-0-(4-0-methyl-D-glucopyranosyl)-D-xylitol, and cellobiouronic acid is cleaved at a rate one-thirtieth that of cellobiose. Aldotriouronic acids of type (9) are... 

The aldotriouronic acid (5), a derivative of a component of 4- -methyl-D-glucurono-D-xylans, and related branched trisaccharide and associate aldobiouronlc acid derivatives have been studied by... 

Aldotriouronic acid composed of two xylose units and one 0-methyluronic acid unit... 

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