Oligosaccharides chromatography, structure

Table XVI (see p. 56) lists those polysaccharides whose structures have been examined by using the methylation technique and the methylated sugars have been separated as their methyl glycosides. In a few studies, g.l.c. has been used only to check on the identity of fractions separated by column chromatography. For convenience. Table XVI is subdivided according to the type of polysaccharide involved. In a similar way, Tables XVII (see p. 72), XVIII (see p. 76), and XIX (see p. 79) list those neutral, acidic, and basic oligosaccharides whose structures have been investigated in like manner by using g.l.c. Typical retention-times have been tabulated. ...

Although structures 3, 10, and 12 exhibit different compositions, their hydro-dynamic volumes are very similar. The hydrodynamic volume of an oligosaccharide can be determined via the determination of glucose equivalents by means of ion-exclusion chromatography. Structures 10 and 12, which differ by only 0.1 glucose equivalents, can easily be separated by the HPAE-PAD method, whereas the separation by ion-exclusion chromatography is extremely difficult. 

The structures of many oligosaccharide chains can be elucidated by gas-liquid chromatography, mass spectrometry, and high-resolution NMR spectrometry. Glycosidases hydrolyze specific linkages in oligosaccharides and are used to explore both the structures and functions of glycoproteins. 

Blanken, W. M., Bergh, M. L. E., Koppen, P. L., and van den Eijnden, D.H., High-pressure liquid chromatography of neutral oligosaccharides effects of structural parameters, Anal. Biochem., 145, 322, 1985. 

After the release of the oligosaccharides, they must be purified by a variety of methods before structural analyses can be undertaken. Ion-ex-change chromatography, gel-filtration chromatography, or some type of electrophoresis is usually used for the purification. At this point, structural analyses may begin. 

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