Abstract
The presence of O-acetyl ester on fucogalactan was suggested by IR spectrum and confirmed by gas-liquid chromatographic analysis. The determination of acetyl ester revealed the complete molar composition of fucogalactan to be fucose:galactose:acetic acid=1:1:0.6. Sequential Smith degradation of the deacetylated fucogalactan gave a polysaccharide resistant to periodate oxidation, except for the terminal residues, suggesting the presence of a 1→3-linked core galactose-chain. Gas-liquid chromatographic analyses of hydroxy- and oxo-compounds produced by Smith degradation showed that all fucose residues were located in the side chains with some of galactoses. Further, every side chain was shown to be mainly composed of 1→2-and/or 1→6-linked sugars and terminated with fucose residue. These structural features were consistent with the results of linkage analyses of the partial acetolysis products from fucogalactan. The deacetylation of fucogalactan reduced greatly the intrinsic viscosity and increased the sedimentation coefficient.
