Isolation and purification of sialic acid

Both methods, NMR and FAB-MS, require preparation and purification of individual sialylated oligosaccharides, glycopeptides, or gangliosides before analysis, making this approach less attractive if only low amounts of the corresponding materials are available. Therefore, sensitive methods for isolation and analysis of sialic acids and sialoglycoconjugates are required. Several HPLC methods have been developed that fulfill this need. 

Exact analysis of sialic acid is required in biologieal experiments where the biological role of sialic acid is frequently studied with the aid of sialidases, and the amount of sialic acids released is determined. This is also important for periodate oxidation studies on biological systems, where modification of sialic acids by periodate is only assumed, but chemical analysis of this effect by isolation and analysis of the modified sialic acids is seldom performed. These uncertainties in determinations of sialic acid can be overcome by the purification procedures already described. Furthermore, it must be stressed that unequivocal determination of the structure of a sialic acid, especially... 

Although most of the sialidases have been purified by classical methods of enzyme isolation, affinity chromatography is now coming more and more into use, as is indicated by the foregoing examples of purification of sialidases. The adsorbent first used for chromatography of sialidases was sialic acid bound to the surface of intact erythrocytes ... 

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