Gangliosides sialidase action

The aeylneuraminic acids can be released from their glycosidic linkages either by dilute (aqueous or methanolie) acids or sialidases. Special care must be taken in the isolation of the rather labile, O-acv-lated sialic acids, which arc partially non-susceptible to the action of sialidases. Furthennore, in gangliosides, non-O-acetylated sialic acid residues occur, and these are also more or less resistant towards these enzymes. 

Figure 12. Time course of NeuAc release from liposome-associated ganglioside Gn,a by the action of Vibrio cholerae sialidase...

Sialidase activity has been detected in certain invertebrate species. A recent study has demonstrated that the leech Macrobdella decora contains not only an ordinary sialidase, but also a novel sialidase which releases 2,7-anhydro-a-A-acetylneuraminic acid from various sialoglycoconjugates (Li et al., 1990). The purified enzyme has a molecular mass of 84 kDa and shows strict specificity for the a2-3 linkage in Neu5AcLac and gangliosides the enzyme does not cleave the a2-6 and a2-8 linkages (Chou et al., 1992). The mechanism of action of this enzyme is unknown. 

Heijlman, J., and Roukema, P. A., 1972, The action of calf brain sialidase on gangliosides, sialoglycoproteins and sialoglycopeptides, J. Neurochem. 19 2567-2575. 

Lipovac, V., Barton, N., and Rosenberg, A., 1973, Control of the action of Vibrio cholerae sialidase on mammalian brain gangliosides by ionic strength. Biochemistry 12 1858-1861. 

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