Oligosaccharide degradation product, methylated

Xyloisosaccharinic acid [2,4-dihydroxy-2-(hydroxymethyl)butanoic acid] is one of the major, alkaline-degradation products of wood xylan, in particular, that of birch. The disaccharide, 2-O-D-xylopyranosyl-L-arabinose, which was isolated as a hydrolysis product of corn-cob hemicellulose, is readily degraded at 100° in 15 mM Ca(OH)2 to acidic products, primarily saccharinic acids. Xylan oligosaccharides from corn-cob hemicellulose produced 2,4-dihydroxy-2-(hydroxymethyl)buta-noic acid when exposed to 0.02 M Ca(OH)2 at 25°. However, it was noted that the xylan, itself, was stable at 100° in Af NaOH. The major acidic component of the hemicellulose fraction of slash pine Pinus el-liotti) after acid hydrolysis was identified as 4-O-methyl-D-glucuronic... 

Figure 2. Methylated oligosaccharide degradation product obtained from the incomplete Type III streptococcal antigen (9)...

The oligosaccharides (11) and (12) have been isolated from the degradation products obtained from cellulase treatment of the L-arabino-D-xylo-D-glucan from tobacco leaves, Their structures were determined from the results of methylation analysis both before and after reduction with borohydride ion as well as by and n.m.r. spectroscopies. Present in the hemicellulose fraction from the endosperm cell walls of rice was a D-galacto-D-xylo-D-glucan. This polysaccharide was based on a (1-> 4)-j3-D-glucan backbone to which were attached residues of D-xylose and D-galactose at 0-6. 

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