Glycoconjugate isolation

Figure 9. Structures of additional glycoconjugates isolated from Riesling wine during this study B-D-glucopyranosides of 3-methylbutanol 21, 2-methyl-butanol 22, benzyl alcohol 23, 2-phenylethanol 24, furanoid linalool oxides (two diastereoisomers) 25, pyranoid linalool oxides (two diastereoisomers) 27, 3-oxo-7,8-dihydrc>-a-ionol 28, 3-oxo-a-ionol 29, 4,5-dihydro-vomifoliol 30, vomifoliol 31, and 7,8-dihydro-vomifoliol as well as the 6-O-B-D-apiofurano-syl-fi-D-glucopyranosides of furanoid linalool oxides (two diastereoisomers).

Oligosaccharides and glycoconjugates in living cells often exist as closely related mixtures. Their isolation from natural sources in homogeneous form is therefore very difficult, involving tedious purification and difficult characterization. This sequence of steps tends to result in low yields. This difficult situation presents chemical synthesis with a major opportunity to positively affect progress in the biochemical understanding of the processes described above.4... 

Of the many areas where these methods have been useful, the greatest impact has been in the area of complex plant and animal oligosaccharides, glycopeptides, and other glycoconjugates (see Table IV). The isolation of these pure carbohydrates, by the methods described, has allowed their spectroscopic, chemical, and enzymic analysis, in many cases for the first time (see Addendum). 

A method for selective, radioactive labelling of sialic acids, especially in cell membranes, by mild oxidation with periodate followed by reduction with borotritide, has heen described by Gahmberg and Andersson.200 This procedure can be used either for isolation and characterization of the labelled, cell-surface glycoconjugates (see, for example, Ref. 201) or for autoradiography of tissues and cells (for example, erythrocytes).142... 

Peumans, W. J., H. C. Winter, V. Bemer, and L. Van-Leuven. 1997. Isolation of a novel plant lectin with an unusual specificity from Calystegia sepium. Glycoconjugate J. 14 259-265. 

In the literature, there are several examples of partial hydrolysis of polysaccharides or glycoconjugates containing 2-amino-2-deoxyhex-ose residues. One example is the hydrolysis of carboxyl-reduced, N deacetylated chondroitin, with the formation of 4-0-(2-amino-2-deoxy-/3-D-galactopyranosyl)-D-glucose.51 Another is the isolation of 6-0-(2-amino-2-deoxy-/8-D-galactopyranosyl)-D-galactose after N-de-acetylation and partial hydrolysis of the pentasaccharide (19) obtained... 

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