2.4- Di-O-methyl-D-galactose

O. 3 0.6 0.5, respectively, as well as 2,4-di-O-methyl-D-galactose. Each polysaccharide contained, in addition, 10% half-ester sulphate and ca. 0.5% protein. Structural studies showed, inter alia, that the D-glucuronic acid residues were linked to 0-3 of the D-galactose residues and that 2-0-methyl-D-glucuronic acid residues were linked to 0-4 of the L-galactose residues. The polysaccharide from... 

A series of polysaccharides have been isolated from the sea grass, Phyllos-padix torreyi, which are unusual in containing residues of o-apiose (2—28 One of these polysaccharides had the composition, L-rhamnose, L-arabinose, D-xylose, D-apiose, D-galactose, and D-mannuronic acid in the molar ratio 4 1 5 2 4 9. Of the D-apiose residues 80 % were oxidized by periodate and the major neutral sugar residues found in the hydrolysate of the methylated polysaccharide were 2,3,5-tri-O-methyl-L-arabinose, 2,5-di-O-methyl-L-arabinose, 3,4-di-O-methyl-L-rhamnose, 2,3-di-O-methyl-D-xylose, 2,3,6-tri-0-methyl-D-galactose, and 2,4-di-O-methyl-D-galactose in the ratio 1 1 6 6 3 3. 

In agreement with the earlier findings,126 approximately equimolecular proportions of 2,3,4,6-tetra-, 2,3,4-tri-, and 2,4-di-O-methyl-D-galacto-pyranose were isolated as the main products of hydrolysis of methylated e-galactan, but, in addition, small proportions of 2,3,4-tri-O-methyl-L-arabinose, 2,5-di-O-methyl-L-arabinose, and 2,4,6-tri- and 2-mono-0-methyl-D-galactose were found. Evidence in favor of partial structure XLI for the galactan framework was obtained by application to the polysac-... 

This structure was established by periodate oxidation and methyla-tion, followed by hydrolysis, as already mentioned. The formation of 2,4,6-tri-O-methyl-D-galactose and 2,6-di-O-methyl-D-galactose gave particular support to this structural proposal. 

On the other hand, ganglioside-G, is structurally similar to ganglioside-G,. By treatment with neuraminidase, one molecular proportion of N-acetylneuraminic acid is cleaved, resulting in ganglioside-G, but, after methylation with subsequent hydrolysis, 2,3,4,6-tetra-O-methyl-D-galactose and 2,6-di-O-methyl-D-galactose were isolated. 

An L-arabino-D-galactan, in 2% yield, has been isolated from the fruits of Dillenia indica. From the results of partial acid hydrolysis and methylation analyses, when 2,6-di-O-methyl-D-galactose, 2,3,6-tri-O-methyl-D-galactose, 2,3,4,6-tetra-(9-methyl-D-galactose, and 2,3,5-tri-O-methyl-L-arabinose residues in the molar ratio 7 3 1 8 were identified, it was concluded that the polysaccharide was a (1- 4)-j3-D-galactan that contained L-arabinofuranose residues linked at 0-3 of some of the D-galactose residues in the main chain. 

Di-O-methyl-D-galactose 3,4-Di-O-methyI-D-mannose 3.6- Di-O-methyl-D-mannose 2... 

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